I have found a procedure that works for me and keeps propane use to a minimum. At night I crank up the furnace to about 65-70 degrees. Most evenings I also take a hot shower. Then at bed time I turn the furnace off for the night. I warm the bed with one or two large hot water bottles. I have found really warm blankets. Pendelton sherpa fleece blankets are really warm and very light weight. Two blankets will handle about any temperature. (I believe these are still available from Costco at about $35 each. By morning the camper temp might be in the 40s. I crank up the heat, sit next to a vent and after breakfast I turn the heat off for the day. This procedure works well for daytime temps roughly in the 30s and night time temps roughly in the 20s. Colder than that and it is time to leave for warmer climes.