We have had or Fleetwood Discovery 40G for a year now. Last Thanksgiving we went on our first semi-cold trip. I could not keep my feet warm, Heat on full furnace mode, wool socks, Uggs, a blanket stuffed around my feet still cold feet. It was terrible.
I found to my surprise (not really a surprise) that there were several holes in the firewall from the factory. 2- 1 inch holes and a few wire holes that had net been sealed properly.
My plan, foam the big holes, silicone the small ones and add 3/4" R4 Foam board to the exterior of the firewall.
I bought I sheet of foam board, a tube of silicon, a can of foam spray, 1 box of 1 1/4" screws and a box of 1 1/2" washers.
The screws would go right through the foam without the washers.
This took me about 2 hours to complete and should be night and day difference this year. We ware about to head to VA from TX for Thanksgiving so it will test the project.
I also had a difficult time last year keeping the wet bay from freezing during the quick cold snaps before i was ready to fully winterize so I did this;
Bought a reptile cage warming pad, 2 - 12x12 ceramic tiles, put the reptile warming pad between the 2 tiles and duct taped the edges together. WA--LA
Ceramic heater that hold 86 to 100 degrees.
I put some foil backed insulation wrap in the bottoms of the compartment to help hold in the heat and it worked like a charm for 100$
Here is a link to what I used.
Here is how it looked completed.