Hi mchero,
I use electric heated carpets.
The safest heaters may be the oil filled units, because their surface temperatures are well below most materials ignition point. They are slow to warm up a room as they rely on convection currents. I tuck them away into otherwise unused spaces by using 1/2 size units. Mine draw 462 watts.
I carry a radiant heater which I love because it heats what it is pointed at. The air is then warmed by heat reradiating from the item being warmed up. They are useful for thawing out a frozen storage panel door, even at low temperatures (tested to -27 c (-17 f)).
I use fan based heaters in several locations. For example my water hose compartment, and the waste tanks. When I know I'll need water I flip a switch and the heater warms the storage compartment.
I don't have any "toe" heaters (base board units), but if I were to continue to full time I'd be moving in that direction.
I do use mechanical thermostats to prevent freezing.
Possibly my best heating modification is the twin window fans that replaced the cold air return grill for the furnace. When they are on they circulate warm cabin air though the duct work and prevent fresh water line freeze ups. Mine is on a mechanical thermostat. I do use a 240 volt bulb in a reflector fixture to keep the water pump protected. It is on the same thermostat as the fans.
I added two extra shore power cords, so I have the OEM 30, a 20 and a 15 amp circuit available for running heat. My peak load is 7100 watts. Average is between 5000 and 6000 watts. Daily usage on Oct 14, 2016 was 3.3 kwh for 24 hours.
Plan well and keep the propane furnace set on at a low temperature in case there is a power failure.
I don't have any issues with moisture. It is -2 c right now and relative humidity inside the RV is 28%.