Get a Skirt: A skirt that goes around the RV will keep cold air from getting under the rig and will help protect the water lines from freezing. For a super easy-to-install solution, check out AirSkirts.
Install Window Insulation: Lots of heat can escape though RV windows. Installing a shrink wrap window insulation kit can help a lot with this problem.
Use Electric Heat: We said before that you will definitely want to run your RV furnace in order to keep the underbelly as warm as possible. That said, you can supplement the heat offered by the furnace with heat from space heaters, along with electric blankets to make things extra toasty.
Check Seals: Before you head out on a winter trip, check all seals. Make sure your caulk is in good shape, replace worn weather stripping, and check on your slide seals. You don’t want cold air to be able to enter anywhere.
Cover Skylights: Finally, we highly recommend covering skylights and roof vents. After all, heat rises, and if given the chance, it will rise right out of the RV.