Rather than the heat pumps, our RV came with the
CheapHeat electric heating system that piggy-backs onto the propane furnace. This system provides basement heat just like the propane furnace with no reduced efficiency at lower ambient temperatures like a heat pump and without using propane. The furnace can be switched between propane and electric heating with a simple toggle switch mounted in the same cabinet as the thermostat.
Used in conjunction with the electric fireplace, it's kept us nice and toasty down to 30 degF so far with capacity in reserve as the furnace and fireplace were still cycling.
Rusty