Annual freeze question - mcc272 please respond

I keep a small cube heater in the camper set on low ,25 outside 50 inside. If I haven't winterized yet and forecast says its going to be real cold I'll turn on the water heater electric element . I don't worry about short dips below freezing . I have the heater on just to try to keep it sort of dry ,40 days and 40 nights of rain is getting old.