The shelf on top of the fridge would get hot when we ran it on propane -- it turns out that the flue vent is under that shelf, and there is no tube conducting the heat and exhaust to the roof. (Apparently, this is how many RV fridges are designed -- it seems odd.) I spoke to a tech, who said that I could create my own deflector to channel the heat and exhaust out to the vent panel on the side of the RV. He also suggested that I add insulation.
It was easy. Here is the area above the fridge, taken from the side of the trailer with the vent cover removed. The top of the flue would be on the right side of the picture, but it is recessed below the opening and is not visible. You can see that there is some insulation on the sides, but none on top -- the yellow insulation on the left was factory-installed, and I added the pink insulation on the right. I sprayed the side wall with spray adhesive and stuck the insulation right onto the wall:
I then stuck insulation to the underside of the shelf. (And yes, the insulation is fireproof -- I tested a scrap and it slowly melted when exposed to direct flame.)
Next, I formed a curved deflector out of a piece of galvanized steel -- I bent it to shape over the edge of my workbench:
Using three small sheet metal screws, I then attached the top edge to the metal plate underneath the shelf. I used double-sided adhesive tape to attach the bottom edge of the deflector to the top of the fridge. The tech told me that I could screw directly into the solid foam insulation atop the fridge, but I did not want to take the risk of puncturing the body of the fridge. Here is the completed installation:
he shelf on top of the fridge is now at room temperature when the fridge is operating, and the flue exhaust streams out of the vent on the side of the trailer. The output from the side vent area is noticeably warmer than it was before, not surprisingly.