I see.
You might look into a small chiller as well. Tandem a couple of old drinking fountains together and add a pump and a water coil......
I use a rear window mount on our Ford and a front window slide-in for the GMC.
I've wondered several times about a system for shore use that was hidden and used most of the vans factory A/C system. A small 120volt compressor teed into the vans discharge and suction refrigerant lines with, possibly, check valves. A converter (120v to 12v) to run a Flex-a-lite type condenser fan and also power the in-dash fan.
The van A/C would operate normally on the road. But show up, plug up and the 120 would power the aux. compressor and fans. The van would be as cool as driving down the road but without any outward appearance of having shore air.
I've never gotten around to figuring up the size compressor required or airflow needed for the condenser fan.
The refrigerant lines could tee together after the accumulator.
N/C solenoid valves could be used instead of check valves.