Looking for advice on best way To keep large toy hauler cool

We used the stand alone unit in the garage in addition to the two roof top units. I built a plywood panel that incorporated the exhaust and electrical connection that fit in the bottom vent door in the garage. Allowed me to run an extension cord to the park pedestal if we had hookups or to a second generator on the odd occasion we were dry camping in heat. My generator and 30 amp trailer couldn't handle the stand alone unit.
The one we used was a black and decker 14,000 BTU.