Where you put the fan is vital to how the refer will perform. The fan must not cool the boiler at the bottom. Cooling the fins near the top will improve cooling. A fan can be installed above or below the fins near the top. Attention to how air flowing in at the bottom is important. Cooling the boiler will hurt efficiency. A thermostat for the fan will save battery power.
Sealing the sides and top to keep a chimney effect is important. For side discharge, a baffle directing the rising air out the side is important. Mine had a baffle, but the corners were open into the inside cabinet. I pushed closed cell foam pieces into all open gaps between refer sides and top.
Proper spacing between the back of the refer and outside wall is also important to keep a good chimney effect and keep the cooling air moving well. Read installation instructions for your make and model. Pay attention to the details in the instructions.
There are some good refer technicians on iRV2. Hopefully they will add to or correct my suggestions.
I wish you good luck and happy trails ahead.