Teardrops n Tiny Travel Trailers

First- helpful background info. I'm building a tiny travel trailer with a flat back wall which will house our single door. I have scrapped the traditional galley in the back in order to have bunks for our two small children. The door on the back wall will be off to one side and a window A/C unit will be installed in the wall on the other. I had initially designed the A/C to be removable, but have now decided that a permanent install is the best route for us. I have seen a number of in-wall installations that attach angled metal into the metal A/C housing, but I have yet to find the details on how this is done. Can I simply use metal screws to screw the angle into the A/C housing? Is there an official "best practice" here?

The best practice will be "don't hit anything inside" with the screws. Each unit will be a little different, but most will have plenty of spots you can run a few sheet metal screws into.

That's what I thought, but having some confirmation makes me feel better. Thanks!

I did some modifications on a 5000 btu unit. Took a few screws out and the workings slid out of the cabinet.This way you could mount the cabinet and reinstall the innards.