I'm not overly impressed with mounting the fans to the access panel. You want the fans as close to the evaporator as possible. in my case I mounted the case fans in brackets made from sheet metal and screwed them to the inner layer behind the Filon outer skin which puts them almost but not quite against the upper evaporator. I also added a lot of insulation to the cavity between the outer cabinet and the fridge body and fabricated an upper baffle to direct and smooth the airflow. In my case, my upper vent is not removable, it's fastened to the camper body with screws. I was looking for maximum airflow with minimal amp draw.