Muddy Flats, If you run your propane furnace only, you should push enough heat down into the compartment area to keep things from freezing up. Some people have trouble with freezing when they supplement their living area heat with electric space heaters which reduces the amount of heat being forced down into the lower compartments with the propane forced air furnace.
If you want to use electric space heaters, put them down in the lower compartments and let the heat rise up.
Winter has really lost it's grip but if you did have a cold blast of 10 degrees or less with a strong wind you could always winterize. It takes less than 10 minutes and 2 gallons of anti freeze.
You can see what the weather guessers are predicting for your area at www.wunderground.com
Here's the weather for Great Falls (if your handle is your location
Great Falls 7 day guess
Good luck and enjoy that beautiful rig!!