Never heard of mounting a receiver on the side of the frame like this for a genset, but as I think about it, pretty nifty idea. I'm gonna assume it's a smaller generator, 3500 or less, as the weight of the bigger ones may put undo stess/twist to the frame mount. But, as for installation off the top of my head, could us a bolt on receiver such as a Curt, or similar brand, make custom L-shaped brackets with one side bolted to the hitch and one bolted to the frame. If measured properly could drill thru the frame and bolt the front bracket thru the frame into the rear bracket. If it were me I'd make brackets, bolt then a little weld to hold it all together.
Happy fabricating, and post up a pic when the project is done!
2011 Coachmen North Ridge 290RKD 5'er
2005 Dodge quad cab dually diesel 6'spd manual
1 weird cat with an occasional attitude problem.