TLDR; Apollo 13 square peg, round hole.

Let’s go.

Instead, Portable AC (or similar):

Start with 1″ insulation board ($30), it comes in 4′ x 8′, bring a box cutter (but not into the store) and cut accordingly to fit into your vehicle.

Rough cut: +1″ on width and height.

Gradually whittle the sides down to get a tight fit. (Not pictured, a heavy piece of cardboard to cut on to protect flooring.)

The portable AC comes with an external vent piece, cut a hole for a snug fit.

Lots of excess insulation board, cut some ‘buttressing’ pieces and Gorilla glue!

One can of white spray paint, three coats. It’s not white, but it’s definitely not as green.

18″ zip ties, cut in half, then attach the ‘middle’ ends with screws for minimal trim destruction, and then tighten the zip ties.

Cleanup, and hook up, and plug it in.

Fin.