Be aware of what happens to battery capacity. Propane boils at -42.5, so production of gas is lower in extreme cold. Having a way to warm the tank is a good plan. I use a magnetic (small) block heater.
The engine may almost certainly need to be equipped with a block heater. Fuel consumption will be higher partly because the air is denser and pushing the RV through that takes more energy.
Enclosed tanks and valves need to have heating from some source.
The fridge needs to be protected from extreme cold or the working fluid may gel and may possibly destroy it.