Insulation above propane fridge

I would just get that aluminum tape and seal up that baffle a little better and see what happens. all your trying to do is make sure the air flow is over the fins and direct it as much as possible to prevent a lot of air from going through with out coming in contact with the fins.  the other thing you can do is add a small low power fan at the top vent to pull air out and increase the air flow through the area.  mine has a thermostatically controlled one so as soon as the outside temp is over a certain temp it turns on, then turns off when the outside temp drops.

but get the baffles sealed up first and make sure the back baffle is the right distance from he fins or it will let to much air bypass the fins.  

My slide-mounted refridgerator had cooling issues. Mobile tech said the problem was hot air from the back of the fridge was getting around the sides and top of the fridge, and the heat was getting thru the poorly-insulated sides and top of the fridge. He filled both side and top cavities with foil backed fiberglass insulation. The idea was that air should come in the bottom vent, circulate up the back, and exit thru the top vent without going anywhere else. That change fixed all of my cooling issues. Highly recommend.

Refrigerators in slides are the most inefficient idea ever. Normally a fridge has a lower vent on the side and a roof vent to allow the heat to escape. In a slide the upper vent is also in the sidewall and doesn't vent efficiently, so auxiliary fans are needed to help with air flow out the top.  That extra space up top may be there to give the heat a better path to reach the upper vent.  

Rock wool. Moisture and fire resistant.