Don t forget the water supply to the toilet. Regular anti-freeze must not be used for this purpose. Propane vapor pressures drop in cold weather. At some point, furnace and hot water heaters will stop working. Water heater plumbing is exposed to outside air temperatures and may freeze and burst.
Batteries are hard to charge in cold weather.
They charge slowly and discharge quickly. Battery loads are high in cold weather. Starting a vehicle engine or auxiliary generator requires more battery power in cold weather. Water supply hoses will freeze if left pressurized and connected to the RV pressure fitting. Holding tanks can freeze, particularly while driving in subzero weather.