This is my first year full timing. I found that last winter in Tucson and then Sierra Vista a small $20 Home Depot space heater was all I needed for my 33’ Class A with no slides. Nights typically were in the upper 20’s to low 30’s. Like HappyKayakers I’d turn off the heater at night and put on extra blankets. In the morning it’d take about 15-20 minutes to warm the rig up. My highest winter electric bill was $44, up from about $15-$20 normally. I was so pleased with the heat provided by space heater that I never used my rigs propane furnace.
I tend to follow the KISS method of doing things.
Steve