As someone has already said the best way to heat your RV is with the furnace. I'd follow that advice and start watching Craigslist.
As far as the Buddy heater I have one that takes one propane canister. They make models that can use a can on each side. I know a guy that has no furnace The buddy is his only heating source. His is connected to his propane tank. Mr Heat make a hose to connect it. I would be sure to buy the hose made specifically for that purpose He seems content. This is what I would do this if you aren't getting a furnace.
I have used mine a few times in my 86 Sunrader. It saves the battery or in emergency if you lose power. The cracked window and moisture on the windows are the biggest draw backs. You can't touch the buddy when it's lit without it shutting off. I had a combo explosive gas detector I think it was $35 before I got the Buddy. As far as temp control I'm guessing you will be able to figure that out. I usually have it on high for a few minutes then keep it on low. I don't care for it really hot.
I would suggest making sure you have the cab blocked off. I just use a thick blanket. No need to heat extra space. The Buddy has worked great for me when needed
The electric one sounds great but you have to have electricity. I am rarely in a position to use juice freely. I always seem to be conserving. The furnace is the best without question but the Buddy is the best alternative I've used. I keep mine in the RV with a couple of cans just in case.
