" An electric heater that would run from the generator if I ran out of propane entirely. I would likely have it run directly from an extension cord so there isn't any chance of overheating the rig's electrical wiring"
If your wiring is in such poor condition your afraid to plug in a heater you have bigger problems then ice storms. Your likely to create nothing but grief by running extension cords and propane lines. Your camper should be wired with 14 AWG wire .... your extension cord 16 or 18 AWG ..... much lighter wire not rated to carry 15amps.