Regarding the fueling issue, I have a Fleetwood Flair 29M which is a slightly larger version of your HR. When I first got mine, the fuel fill pipe was collapsed and it wouldn't take fuel. I had to get under it, loosen the hose clamps, and straighten the pipe. I wonder if it is related to your venting issue.
That coach does look like it has a lot of weight on the driver side...both slides, the generator, bed, driver compartment. I think the corner-weighting suggestion is sound.
2021 Fleetwood Flair 29M
2014 Silverado 1500 toad