We have a tank heater, use it whenever we are expecting freezing temps (which we try to avoid). We don't boondock in this kind of weather. As we are small, we use a tiny electric space heater for heat---if you are plugged into and paying for electricity, why use your propane? We have seen some really cool electric space heaters which look remarkably like wood stoves, put out an amazing amount of heat and add a lot of atmosphere to the interior in cold weather.
