We don't get many days where the temperature stays below 32F, so we keep our rig plugged in. We have a deLonghi oil-filled radiator sitting in the kitchen area towards the bedroom end and I got a plug-in programmable digital thermostat. I have it set to its minimum of 45F all the time.
During the colder overnights, my Killl-a-watt shows we burned off some watt hours, but the remote thermometer (I have the base unit in the house) showed the internal temp near the driver's seat never went below about 34F, even on a couple of 26F outside temps.
I'm happy with this set-up.
Frank and Eileen
No longer RVers or FR owners