The window-wart AC in a vehicle - especially if it never had AC from the factory in the first place - is something I can understand. Ugly AF, but at least it’s functional.
The generator on top? What TF is up with that? Surely it would be simpler to swap out the alternator for something more powerful that can push up to 15A on a 110V converter.
12v boat motors are for only trolling. So technically it powers a boat, but not really... They're typically only 1hp. You could get a 1hp AC, but they're not designed to run on 12v. You'd need to change DC to AC and then step up to 120v at least.
You'd run out of power pretty fast either way if you're planning to use the AC for extended period of time, just like trolling motors. And no quick way to recharge. Alternator suggested above is somewhat realistic as some cars actually do come with a 120V outlet (albeit at limited wattage not enough to power a full sized window AC). Though, all of this is rather inefficient setup and burning more gas.