If I were to add a generator option designed for Wallydocking, I'd look at adding a second alternator to the house batteries, then a whole-house inverter so I could run the A/C from that. That way, if it is hot at night, one can just run the vehicle's engine and take power from that, and people care far less about a car engine running than a generator.
Plus, there is the issue of theft and vandalism of generators. A running construction generator makes one's presence known to people... and being the subject of attention isn't a good thing, as it attracts both security, police and criminals. An inverter generator isn't as noticable, and if you buy a good hard start kit, Micro Air Easy Start model, which can allow a generator to start and run from a 2000 watt Honda.
Onans are variable. It is all about how the generator is installed. If the installer uses acoustic dampening stuff, shock mounts, a resonator, and shock mounts on the cords and exhaust pipes, it can be 15-20 decibels more quiet than one just shoved in a compartment.
I wish Onan would do a re-engineering, and go with an inverter system, perhaps with a large capacitor system so it can handle 60+ locked rotor amps from A/C compressors. That way, the engine doesn't have to run at 3600 RPM all the time, but can run at whatever RPM is needed.