I did something similar - I got one of those attic thermostats that are used to turn on a fan when the attic temperature gets to a preset temperature.

I set it to 80 degrees for my compartment where the converter chassis is at.
When the internal temperature get above 80 degrees it turns on a 6-inch 12VDC axial fan and exhausts the hot air out a vent in the outside trailer wall.
I used a 12VDC FAN so that all of this will work the same if I am at a shore power site or running on batteries off the power grid.
I used one of these TRAILER WALL VENTs that you find on most RV's where venting to the outside is required.
