I have spent a LOT of time researching using a small window AC unit converted to work in a camper van without cutting a giant hole in a wall. There's a fellow on Youtube[1] that did this successfully, and he's the only known example of it that I've seen, and he was only able to because was he a professional HVAC technician and had several unique tools you'd never own if you weren't an HVAC tech.

Essentially what I'm aiming for is this: https://www.cruisencomfortusa.com/hd-series

which is a perfect product, except that it costs $4000 and still uses 20% more power than some of the smallest window units. It's ridiculous that the major difference between this $4000 unit and a $150 window AC is that the $4k version has a rubber hose connecting the compressor to the condenser coils instead of the typical thin copper pipe. I am sure there are other differences - it uses better components that are more suited to a moving vehicle with shocks and vibrations, has a strong compressor to deal with the longer hose length, and is already adapted to run off of 12V. But a $3850 price difference is ridiculous.

As the fellow on Youtube has shown (it's been in his camper van for years without a problem) there's really no reason the components from a $150 window unit won't work.

Whenever I finally do a camper van build I'm going to find an HVAC tech who can help me with a couple steps (mostly removing and then re-adding refrigerant) and convert the copper pipes to PTFE lined stainless braided hoses attached to SAE fittings. It may not work, and I've heard finding an HVAC tech to work on weird projects is very difficult, but I want to give it a try.

[1] https://www.youtube.com/watch?v=AXgHIrFqm9o