piano, the tank is below the floor, and it has never frozen. We have camped many times when the temp gets down to 10 or 15 degrees F., but never below that, and it is almost always in the 30s during the day. My concern is that after many hours of sub-freezing temps, my good luck will run out. I will insulate as much as I can, but insulation does not raise the temp -- it just conserves warmth.
I am currently looking into low-wattage heating pads. They all seem to run off of 120v, so I would use the inverter, I guess.
