You can only run X amount of electric heaters so where are you going to get the supply amperage? In those types of temperatures you have to throw fire at the problem. LOTS of fire! jimo
I was in Colorado last year in November when it dipped to 5 degrees. I have a reglur ole FW thats not made for winter and I was using 30 pounds of propane per day and also running a 1200 watt electric heater. On the worse nights I was running another 1500 watt heater on my gen under the holding tank area. I had boxed the tank area in with black celotex(?) board from the Depot.
I cant image what you go through in the winter but if I had to do it again I would concentrate on building skirting wall all the way around with foam panels and spray foam every gap. 2" foam board or more. It may only give R7 or so but it would probably help a lot. I also covered the windows and vents with that silver looking roll insulation from HD. It was like living in a cave but it helped a lot. At night we put a quilt over the door area.