Yeah, like Huntingdog states, adding insulation to the underbelly area will greatly increase comfort in the cold.
FWIW, I added 1 1/2" extruded foam and sheets of Luan plywood to my hunting partner's old travel trailer under the floor. We were hunting in MN, a stones throw from Canada. In Nov., it can get as low as -20f up there. Insulating the floor made a heck of a difference and our boots didn't freeze to the floor anymore. One year, in the back storage area underneath a bunk, everything liquid froze. After the insulation, that area remained tolerable. Insulating the floor makes a huge difference in comfort and lowers the propane consumption.