I’m not sure what you will accomplish.
Higher load rated tires normally require higher tire pressure (assuming same size), which will make the ride even stiffer, and that’s already a problem. And if you don’t use higher pressure, the load capacity will be wasted.
Besides, if your recommended tire pressure is only 82 PSI, it means you already have excess load capacity since those tires can be inflated to higher pressure, but would also make ride harsher.
Regarding the lean, your motorhome has a slide in rear of passenger side (I think), so it’s very possible it has a bit more weight on that side. I recommend you get the motorhome weighed on all four corners before starting to make “upgrades”.