Very creative. Couple things in there that are food for thought for my continual buildup.
The fridge/bed slides were designed and built exactly the same as the drawer slides. There are a series of roller bearings which support a length of 1' square tubing which is attached to the side of the slides. You can see the bearings and a side shot of the drawer in the pictures posted previously. I can post additional pictures shortly.Could you show a pic of the slider that holds the fridge with the fridge on it? How and where are the supports to hold that amount of weight? Pictures would be awesome.
I found our heater at Princess Auto - a Canadian auto/farm supply supplier. Link to heater is here. Try googling something like "auxiliary air heater" and see what you can find. Heaters like these are common up here for school buses, farm tractors, etc. Good luck!Where did you get the topper heater, or any guidances of where to look?