EMD360, if the 22' rv was on a 350 and the 26' is a 450, then that might be why you feel the difference in ride. Maybe ?
Regarding potholes,
you're driving a truck with suspension to haul a home. It's going to feel a bit rough at times. It has to be stout enough to haul its weight. These mods that we are doing, all may help a bit but at the end of the day...it's still a truck !
My mods included the larger sways, Koni's in the rear, Bils front, steering stabilizer , rear track bar , a good reputable positive caster alignment and I run my psi in my 24 ft class c, a little softer because I'm underweight by 2000 lbs,.
I run 75 lbs Rear and 70F.
IMO, the rear track bar, which I did at the same time as the shocks, gave the most bang for the buck. That combined with the lower front psi to 70 seems like its offering more footprint on the pavement, resisting be pushed by passing bow-waves.
*But, as said here by someone else, try to leave as much room between the other vehicle next to you at the time of passing . Doing that allows the wave to dissipate a little.
Today, my 24' C drives real nice, even on the 'back road twisties', it feels pretty solid up to 105-110 mph. but that might be the unbalanced tire on the toad. :W
Seriously, I'm restricted to 65 mph towing my toad as well when towing my 5x12 v-nose.
Stay safe, Bob.