Dry Camping - Heat with Propane, or electrically w/Inverter?

I would not want to run a Mr Buddy or similar unvented heater while I slept. In fact I rarely run my furnace at night. Instead I keep the RV fairly warm in the evening then I turn it off at night. I have a couple of oversized hot water bottles to warm the bed and I have a pile of blankets. I rarely camp when it is colder than the about the upper 20s. Even so it might be down to the low 40s in the RV when I first get up.