Update: Every thing is going well. When the temperature is over 25 degrees, the skirting keeps the bottom of the Casita
above freezing, so I don't have to worry about the plumbing. Above 25, I run a 1500 watt space heater inside the Casita
, and use propane in the water-heater (it acts as a little furnace
under the Casita). I use a Holmes 1500 watt heater ($45 on AMZ), which seems way more solid than the $20 heaters at Walmart).
Below 25, I turn on the 1500 watt space heater under the Casita, aimed at the valve. I also started putting RV Anti-Freeze in to the Grey/Black tanks immediately after dumping, so the Anti-Freeze goes to the valve.
The propane tank gauge seems frozen, and just says the tanks are full, so I just have to let it run out without warning. The gauge no longer cuts off the propane since I put the heat-tape on it. The whole regulator is wrapped in heat-tape and Reflective. I got heat-tape that only heats enough to keep it at 45 degrees.
When it gets below 20, I use the inside propane furnace
instead of the space-heater. With the furnace
and hot-water heater on, it was 80 inside when it was 10 outside.
I have 5 space heaters, though I only use at most, two at a time. The Holmes is way better than all the others. It has a wide base, so there is no chance of a tip over. The other 4 are $20-$30 ceramic heaters. I put a toilet-seat under the Casita for the space-heater to sit on. It keeps it high enough, and water/condensation easily rolls off. The skirting hides the toilet seat.
We are expecting a lot of snow in the NE this weekend, but I'm not worried. Everything is okay when it's over 25 degrees. As long as I have city water coming in, sewer lines working (not frozen), and lots of electricity, I'm fine. If I wasn't able to use the electric power from two lots, I would run one space-heater underneath, and use the heat-tape to keep the propane gauge working. Then I would use the propane furnace to keep the inside warm.
One weird thing I noticed, using propane in the hot-water heater seems to increase the water-pressure, so it "shoots out" when you first turn on the hot-water. I suspect that increased pressure caused some of my water leakage last month. Now, I turn on the hot-water to release the extra pressure every 6 hours or so. The electric water heat did not do that.