Skiphoyt, I can’t remember where but I read they are starting to modify AC systems in the c24 to run the AC from an inverter. Exactly what you said, keep RPMs up to get alternator amperage up so batteries remain charged. The soft start system probably helps the compressor kick on without such a harsh amp draw (capacitor maybe?). You will probably only get 4 hours and I’d install a Victron shunt so you can easily monitor battery conditions. I have my shunt connected to my house bank only but you can connect multiple banks. I would think that could be a good way to destroy batteries if you drain them too far.
My victron shunt is Bluetooth so I can monitor batteries from my phone. Also, I can run my AC fan off my inverter. The compressor will not run off the inverter but I use the fan to circulate air.
It sounds like your issue is not starting and running the AC from your inverter, but water flow. Sometimes if you turn hard the water pick up comes out of the water so your pump may lose prime. Have you checked the pump at slow speeds or stopped? If the pump works and the system works at slow speeds you may just need to go slower or avoid sharp turns. I’m not sure a scoop will be practical - I’ve never heard of one. I have heard people relocating their thru hulls... which doesn’t sound fun.
If you’d like more information on a shunt let me know.
Lastly, I looked at a 2007 scout aback 262 that had a factory installed Marvair AC system that ran off battery alone. The technology exists so this isn’t surprising.
Good luck!