I saw this in a new Cabelas catalog I received a day ago. It is a digital controller that hooks up to a small digital window air conditioner mounted through the wall of a box trailer or small building to make a walk in cooler. If you could find a used box trailer in good shape all you have to do is insulate it and mount the AC unit and hook it up to the controller and you are good to go. You could even take it with you if you have a generator. The catalog has a picture of the set up but they don't have it on their online catalog so I pulled this off the net.

https://www.storeitcold.com/mobile-guide/

The coolbot is $330 and we did the same thing but found a way to make it cheaper.