It'd most likely be easier to run the mini-split or window units off of the generator. That way when you can connect to shore power you could still run the ac without running the generator. It also simplifies it by not having to do the math on compressor and condenser sizing.
You can buy 10kw belt driven gen heads for less then a grand.
I'd suggest the belt version for simplicity. You can find and mount pulleys easy enough. It also enable you to run the engine at less rpm which would reduce noise and heat production.
The other option would be mounting it directly to the flywheel. But that would require a bellhousing of some sort(might be non existent) and that has to be aligned almost perfectly, so anything custom would have to be fairly precise. This would also have to be ran at 3600 rpm, unless you have a 1800 rpm head and those aren't cheap.
I'm doing something similar. I bought a pair of apu's for scrap. One was a carrier unit that had just an alternator and ac compressor mounted. The other came with a 4kw gen head along with the alternator and compressor. I bypasssed the compressor on the second one with an idler pulley and am currently in the process of mounting it under the bus as an onboard genny.