Most of the power used in a AC unit is used by the compressor. I'm not sure I understand why RVers think it is good to run a engine to turn a generator to run a motor to turn a compressor. Every time you change from mechanical to electrical and back energy is lost. Why not use the engine to drive the compressor? Then a much smaller alternator would take care of the rest of load.
BTW, years back I heard there was a battery powered AC unit for truck sleeper. When I checked in it was only available as accessory on new truck so I didn't much look into it, but the technology is out there.
Take the coils out of 12V fridge, build dog bed around them...
