Now we understand what you want to do. BAD IDEA.
1. The furnace boards have been designed to take the heat and have been for almost 25 years. It is rare for a furnace board to fail
2. That "housing", if you look at it has numerous vents and cut outs. That is for the furnace to PULL the interior air over the combustion chamber, heat that air and throw it out the furnace ducts. If you try to insulate, it will not only stop that cold to hot circulation, it will also OVERHEAT the area around and the combustion chamber. Then your furnace will short cycle(hi limit kicking in and out) the combustion chamber and take forever to heat the RV. Doug
