IMHO. The best bang for your buck would be 2 of the Champion 3500w units. I base this on the fact that you stated this is for emergency use, not that you would depend on one for typical camping use. Having 2 gives you more options about placing them when they would be in use. You wouldn't have to stretch out long extension cords to reach your trailer and the appliances in the house.
Should you want to quiet them down, Supergen makes an enclosure specifically for them Tent.
I had a Reese Dual Cam HP hitch w/ 1200# bars on it. Even with that I was buffeted by gusting cross winds and when being passed by trucks. I upgraded to Pro Pride 3P Hitch. It has made a huge difference in how the trailer behaves.
I do a lot of festival camping where a 15 amp service is all that's available. To avoid lots of issues (breakers tripping) I do the following: The air conditioner stays off. Keep the refrigerator and water heater on propane. Limit the use of the microwave, coffee pot, electric skillet or griddle and let's not forget hair dryers and curling irons to one at a time.
Additional extension cords are usually necessary. A 10 gage cord is best and a 12 gage is acceptable.
I had a similar problem. The issue was a dirty gas orifice. Pulled furnace out and disassembled. Cleaned the burner while it was out and removed the gas line from the control valve. Used some spray carburetor cleaner followed by compressed air. Great heat now.
The cover is for use with a Dutch Oven. Works great in windy conditions. I bought mine mainly for use with my DO's. The propane burner is great for use with large pots. I've had mine for 3 years now, very satisfied.
Leaving Tuesday for MB but Sunday night lows are suppose to be lower 20's. Will running an electric heater & furnace be enough protection? I do have enclosed underbelly. What if I were to turn on hot water header? Would that cause any harm? Help any?
I'm headed for MB myself tuesday. Been getting the trailer ready today. Had planned on connecting water today but not with it going down to 24 here.