I just caught you post.
We have the same generator, no insulation, noisier than heck. We take our 3000 watt Honda when we are having to run the generator a lot because it is so much quieter.
If it's a short stay, 3-4 days we will put up with the Onan but if it's a week or more we just take the "quiet" one. I wish the Onan wasn't mounted under our bed because on a hot day you can't take a nap with it running, actually you can't do anything with it running but run the microwave and A/C.
This is where we like our solar panel, it keeps the batteries charged so we don't have to run the gen to keep them up.
Days camped in 15-180 days-16-95 days
2016 t28FQDX Shockwave, New Provider tires 10/31/18 ,TV-2015 LTZ Duramax with over 156,000 miles, with delete done, 2014 Polaris RZR 800 EPS/ 11,700 miles