I have had about a dozen trailers since '77 but I wanted to try a 5er so in 2005 I got one then decided it was to much trailer for my F250 SRL so I went out and bought an older ('99) 7.3 PS F350 dually, I felt better towing it but was still underpowered. I kept it for about 4 years but never liked it so I sold it and bought another trailer and now on my second trailer since. I have a trailer that has steps going to the bedroom and bathroom but it does have basement storage in the back 1/3 of the trailer and only 2 steps into the trailer.
Open Range makes several trailers and 5ers that have a sliding door and a deck. Their longest trailers are 36-37 feet I have their one of their 36 foot. I went from a 27 foot to it and I ended up getting a ProPride hitch to help manage, the total length of my rig is 58 foot and like a lot of people have said most stats and national parks will not let me stay there because I am over 30-34 feet but I have never had a problem finding commercial a park to stay at. I just look for big rig friendly, we have been on two 3 month trips and put on over 16,000 miles on them. Now a few parks I had to park my truck in the visitor parking and a couple were just barely long enough for my trailer but I managed to get it in.
I have an Open Range JT340FLR that I tow with a F250 and I have had to add air bags to my truck, I also bought a ProPride hitch, it's like a Hensley. The trailer does have a heavy tongue weight I had 1400lbs equalizer hitch that I could not tighten enough to get my truck level that is the reason for the air bags and now I am level. My loaded trailer weighs around 11,800 lbs and tongue weight is around 1500 lbs