I am very sensitive to sound and would not take one of the RV type generators for free! I personally have a Honda 2000 in a sound box. I also find the RV AC's to be the equivalent of a 747 at takeoff and use a window AC, which the little Honda runs with ease.
I have built a couple sound box's for my RV's and there is quite a bit to it. Your best option is to Google generator sound box's, generator sound proofing, DIY generator enclosure to get a handle on what is needed and different ways to go about it.
Lots of options depending on how much time and money you want to put in it.
Some add a different muffler and are happy, some use heavy material to dampen the sound and some use $$$ material while channeling the intake and exhaust around corners. Sound canceling headphones might also be an option?
