I'm about 300 miles west of your 10-20.
We just turn the furnace thermostat down, and don't touch the water.
For thermal backup, I've got 2 X 30K BTU gas fireplaces, one up, one down, standing pilot, thermostatically controlled, set to fire up at just slightly lower than the furnace thermostat setting. If the power were to go out, the 2 fireplaces can heat the entire house, and keep the pipes warm. We hardly use our furnace in the winter at all any more, it's become the backup. We let the fireplaces handle the heating, and just keep it for summer cooling.
I can check the temperature via remote security camera access, if necessary.
Mike. Comments are anecdotal or personal opinions, and worth what you paid for them.
2018 (2017 Sprinter Cab Chassis) Navion24V + 2016 Wrangler JKU (sold @ ????)
2016 Sunstar 26HE, V10, 3V, 6 Speed (sold @ 4600 miles)
2002 Roadtrek C190P (sold @ 315,000kms)