I've had the chance to use the heating system now that we've gotten some cooler weather and the heat pump and heat strip will keep the inside of the coach comfortably warm with the oat in the hi 30's. My 35K also has the fireplace with all 3 electric heat sources I should be good until it goes below freezing. One other thing on my Bounder if the difference between the set temp on the thermostat and the inside air temp is more than 5 degrees the furnace will also kick in until the temperature rises.
Remember at 32 degrees oat two things happen. 1. The heat pump goes into lock out to prevent it from freezing up. 2. The water systems is the basement can freeze.
If you expect below freezing weather you must use the furnace to heat the basement and protect you plumbing or winterize the water system.
Brenda & AL
2017 Thor Venetian, T42 "Groot"
2017 Chevy Sonic, 2014 KTM 690 Duke