electric space heater

If freezing out, leaving the furnace on low to avoid freezing water system may not work if you are heating the camper with elec. heater. Furnace won't kick in and then the underbelly won't get any heat - if your heat system includes heating the water storage/pipes areas.
We use the low furnace setting for when we are in transit during freezing temps.

I can only go so long listening to the loud blower motor noise with the built-in furnace.

ALso we always plug-in our portable electric heaters to the camp ground pedestal 20AMP service using a drop cord. Better to use their electric verses my propane to run the furnace. I never shut down the furnace but set it to low setting as the built-in furnace does provide heat thru the underbelly area to keep the tanks warmed up some when it gets really cold.

Roy Ken