Hello,
The Generator needs to be an inverter style so as not to ruin all of your RV electrical/Electronics. Basically, a computer-controlled generator to ensure a constant and accurate flow rate of AC to your RV. Those big-box stores cheap "Contractor power" generators will FRY your RV's power center box and possibly a few appliances as well. Way more dollars in the long run and IT WILL HAPPEN!
Secondly, figure out your wattage needs approximately to size the generator properly. I personally bought a Robins-Subaru 4300ise (Discontinued) and it powered a 30 amp RV with plenty of power to spare running anything and everything including the 15k AC. It even doubled down and powered two 30 amp RV's but I am not sure (Do not remember) if either were also running the AC at that instance.
These are more or less made for the RV industry so they are also Q U I E T!
Here is a helpful link to get you started:
https://healthyhandyman.com/best-inv...r-rvs-camping/
I hope that helped a little.
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