A construction type open cage genny is probably going to be a bit loud unless you park far away from others or you could park by the semi trucks that run their engines all night. There are no generator rules at Walmart and I've heard my share of gennies running, we run our onboard genny as required to keeps us comfortable during the night.
To run most RV AC units 3000 watts is recommended for reliable service at various elevations. Some will pair 2000 watt units to do the job, when AC usage is not anticipated they just utilize a single genny to power devices within their rig. This method is usually the pricier option, but they are far easier to stow and carry than single 3K watt generators.
Our onboard Onan is major overkill with most of our power requirements, we went looking for an inverter generator that could power our AC unit when needed, run quieter, and save on fuel. We opted for the Champion 3100 with remote start, similar to our Onan, we can start/stop genny from within the comforts of our rig. On 3rd year and over 200 hours without any issues.