Consider a tour bus. Most are leases with good maintenance records and were kept in great shape. Bus for sale .com has many prevost in the 250 to 300 range that sleep 12 have have 2 seating areas.
This appears to be the obvious solution. These tour buses are built to handle a large group and are frequently used by bands and entertainers. They don't have slideouts but they have sleeping quarters (bunks) with curtains, private lights and ventilation. They also have huge engines and can pull a heavy trailer.
Most tour buses are built on Prevost chassis, so they can get expensive, or at least more expensive than a top quality coach built for two people.
I'm in the "two six volt golf cart batteries" group.
A six volt and twelve volt batteries are about the same size, but the six volt has three cells and the twelve has six. Since the cells in the 6 volt are larger, they can tolerate the deep cycling much better than a twelve volt.
Costco and Sam's Club tend to have the best prices on batteries. Good luck.
(I have four 6 volt batteries wired to provide 12 volts, but my coach has more electrical stuff and I need that much amperage. As others have posted, don't use the 12 volt option on your frig. Use the propane or 120 volt when available.)
You've pretty much ruled out a defective regulator and a pinched line.
One possibility is your tank contains butane, not propane, which stops "boiling" at about 32 degrees. Butane works fine in the summer, but not so well in cold weather. LP gas has to turn from a liquid to a gas (boil) for it to be available at the appliance. Propane boils down to a way down below "0".
Several vendors in the south sell butane or a mixture of butane and propane. You may have used all of your propane up and now only butane is left.
We have State Farm, which is the second highest rated national company. That's worth something to me. The highest rated is USAA, but they act as general agents for a another company since they don't write policies on RVs themselves.
Read up on auto insurance in a recent issue of Consumer's Reports. You may or may not think the information is unbiased, but that's your choice.
As a rule of thumb, I use the one quart an hour estimate. That's what I was told the 10K diesel generator in my coach uses by a Onan technician at a rally. I can't believe it is that little, but possibly so. I'd even be happy with a one gallon an hour usage level.
I've used the generator on trips to run the house air conditioner and while dry camping out in the desert in Arizona. I never noticed any change in my fuel consumption overall and with a 150 gallon tank, I couldn't tell any change in the fuel level gauge after boondocking for several days and running the generator for several hours twice a day.
Holiday Rambler is a great brand. I've owned two HR products, and have had our present one for 13 years. We love it.
You may want to consider attending a HR Recreational Vehicle Club meeting and/or a rally where you'll meet other HR owners. Search HRRVC.
I second the recommendation to use 6 volt, deep cycle batteries. The larger cells will tolerate the discharge/recharge cycles much better than 12 volt batteries. You'll need at least two to produce 12 volts. Four would be better, but you may not have the room for that option.
The Alfa See Ya had problems with delamination of the side panels. There isn't any good repair except replacement, which is expensive.
As gbopp noted, condition is the most important factor. Check very closely for roof leaks. The damage is very difficult to repair.
Diesel is great for traveling, but if you're going to use it to live in, consider a gas rig. The total price will be cheaper. You'll be able to afford a much newer gas rig, then a comparable diesel pusher just because the chassis of a diesel is more expensive.
We've seen all electric Class A's at RV shows. They have eight house batteries, a household type frig, etc. I'm assuming they had solar panels on the roof, but I don't recall. Obviously, it isn't the ideal rig for boondocking, but at 45 ft and a price of over $500K, the owners probably wouldn't want to do much dry camping anyway.
As for propulsion, a very large diesel is the only good alternative. A quiet diesel generator would keep the batteries charged up.
Normally, electric is more efficient then propane cost wise. However, at some parks we've stayed at, the park doubles the cost per kilowatt that the local utility charges them. That is because the park owns the electrical system in the park, including the posts and the meters.
Still, for convenience, I'd still use the electric option. Otherwise, you'll have to have your propane tank refilled frequently. For us in Yuma, the cost was almost equal in the park. On a private lot, the cost of electric was half. The only exception would be the frig. It is a very efficient user of propane, but uses quite a bit of electric to accomplish heating the coils. So, leave the frig on propane.
Folks, this is why Microsoft is giving away for free, copies of Windows 10 to all owners of 8.1, 7 and, I think, XP. Microsoft knows people aren't going to buy it since all three of those operating systems work quite well, AND WE KNOW HOW TO USE THEM. We've worked thru all the bugs and conflicts. We don't want to do it again, and again, and . . .
Diesel engine in the front - loud. Diesel in the rear - much quieter. I have had a gas motorhome and now a diesel pusher. I could never go back to a gasser.
Drive both to truly understand the difference.
Keeping he cells full of distilled water, keeping the posts clean and storing the batteries charged up. Seems like you've covered everything that's important.
Since all cells produce 2 volts, a 6 volt battery will have three cells and a 12 volt will have 6 cells. Since both are the same size overall, the cells in the 6 volt are bigger and the lead plates are larger, which allows the battery to tolerate deep cycling (down to 11 volts) much better than a typical 12 volt battery.
I have two totally automatic battery minders to keep two sets of batteries charged. (The two engine batteries and my CPAP battery. My coach's house batteries are charged by the inverter/converter.) Both of these work well and I'd recommend using one. They are both totally electronic and automatic. I believe they are rated at 5 amps. That's enough to keep the batteries charged. Since you'll be charging batteries that have been significantly discharged, you may want to consider a high amperage battery tender.
Eventually, you're going to want "more space", and a 45 ft class A is as big as RVs go. It will have a diesel and a diesel generator, and at least a 100 gallon tank. Some coaches have a propane generator which is not anywhere as desirable as a diesel since you can run out of propane very quickly, but not diesel.
Generators are very efficient users of diesel, but they are noisy. You are probably going to want to add solar panels to reduce the running time of the generator.
As others have noted, your holding tanks will be more of a concern than fuel. Class A rigs generally have larger tanks then Class C, and possibly even a Super C.
My 23 yr old rig has a 40 gallon black water tank and 60 gal grey water tank. I believe my fresh water tank is 60 gallons, but my memory is failing me. My fuel tank holds 150 gallons. My wife and I can go two weeks boondocking. It is the black water tank that is our weakest link.
There are only a couple of actual manufacturers, so your real choices are few. If as you say you boondock a lot and have the room, golf cart batteries are your best option.
X2 (While there are only two manufacturers, they make batteries by contract, and make them the way the retailer wants them made.)
I'd also recommend golf cart, also known as 6 volt deep cycle, batteries. The cheapest place I know of is Costco.
You got 8 years out of your old batteries. That's great. I'd also recommend changing the engine batteries as a preventive measure.
Since you've indicated the key is in the ignition and the steering wheel is unlocked, there aren't many other potential causes.
About the only solution I would suggest at this point is to have someone ride in the truck while it is being towed and have that person try and turn the wheel in the correct direction when you make a turn. If the truck's wheels turn in the direction your coach turned, then you'll know it is a "following" problem. That is, the suspension and steering system in the truck won't respond to being pulled around a corner. If that's the case, it is a basic design flaw that probably can't be changed.
On the other hand, the person in the truck may be able to tell right away what the problem is and it could be a simple thing like not leaving the key in the right position.
One point that was touched on here, but not fully explained regards searching of your RV without a warrant. (Of course, the LEO has to have probable cause.)
Our Supreme Court ruled many years ago that a "movable" RV is not protected from search like a residence, even if the owners are living in it. As long as it can be "moved" within a short but reasonable amount of time, it is not protected. Now, an RV that is not movable can't be searched without a warrant.
Now, if this is confusing, don't feel embarrassed. A US Circuit Court got it wrong and Justice Burger had to explain it to the lower court. If the RV is connected to water, power and sewer, it is movable. If the wheels are off of it, and it would take considerable work to make it movable, it is protected. So, if you're on the road and get pulled over, the LEO can inspect your RV, but of course, he has to have probable cause. If he asks for permission, just say you respectfully decline.
Don't take a handgun since possession laws can land you in jail. Instead, take a 12 gauge pump shotgun. You don't need a license. Everyone, especially a potential crook, knows what a pump shotgun sounds like when a round is loaded. So, the sound will scare him away and you won't have to expose yourself or fire a "warning shot". That way, you won't have to explain anything to the police and you'll be safe.
In over 20 years of RVing, we've only been "approached" once and he moved on once we told him we didn't have what he wanted. (I think he wanted a sandwich, or something like that.) I spoke thru the windows, and not at the front door. I kept out of sight. This was in the parking lot of a closed Wal-Mart. We've never had any other incidents. (This may sound cruel, but he didn't appear to be interested in getting a sandwich, but rather in casing our precautions. It was around midnight or a little later.)