Winterizing versus Heating RV Interior

DrewE wrote:
Not a few travel trailers have no provision for heating the water lines at all; they're outside the heated compartment, and there's no basement heat or similar. Not all, of course, but many. If you have one like that, with exposed plumbing, neither the furnace nor an electric heater will do much good.

If the temperature only droops below freezing for a brief bit, and warms up afterwards, you generally have little if anything to worry about for freezing plumbing. There's enough thermal mass to prevent the water from freezing solid in that short of a time. This is doubly true if the unit is designed for cold weather use with the plumbing within the heated and insulated envelope of the trailer, which for a brief overnight cold spell would not dip below freezing.