As with others, we use a Big Buddy propane heater. I installed a quick connect to a fitting that runs a hose outside to a separate 30lb tank that it shares with the camp stove. Provides plenty of heat until we go to bed, at which point we fill a couple of hot water bottles to keep our toes toasty. In extreme cases when we know it will go below 0C, we set the RV furnace to 12C. Do not leave a Mr. Heater running while you sleep!
As reference, I have 6 100A LIFePO4 batteries, with 1200w of solar. Typically I wake up to 70% charge, but we are heavy users - residential fridge, coffee makers, TV and media center, cell phone booster, etc. On a sunny day I’m charged by noon. On a day like today, which is overcast, I pulled out the generator as I was down to 60% this morning (all my percentages of remaining battery are based on available capacity, I set it to 80% to be conservative, or 480AH of usable capacity).
