School me on heated tanks and enclosed underbelly stuff

Some rvs have heated tanks by the propane furnace some have electric pads some have both. If your hooked up to electric and not paying for the electric that's the way to go even if you have propane furnace ducted heated tanks. If your boondocking you better run the furnace to keep the tanks liquid. We only have ducted heated tanks and have never boondocked but if the temps are headed south of freezing we make sure the furnace is ready to go.