We use a little cube ceramic heater with the setting choice of 900 and 1500 watts. We have camped in some cool temp, low of 27 degrees at night in Nov, Dec, and Mar this winter and this heater has maintained the temperature in our TT very well. I switch between 900 and 1500 watts as needed, usually 900 during the day and 1500 at night. Also, in the event of a breaker trip, the propane T-stat is set about 5 degrees lower to keep us warm during the night or the dogs warm when we are not in the TT. I am conscious of load, so I use propane for water heater and will turn elec heater off when using the microwave.