I'm back after a few years of being gone. I originally had a 21 ft. Nomad/Skyline Trailrider toyhauler. Interests changed and life got busy and it sat in storage for a few years and eventually sold it...
I've heard folks use olive oil on the toilet seals. Maybe that has some beneficial sliding effect. FWIW, when I was messing with my old Aquamagic, the return spring broke. That spring was way too much for just returning the flapper. I replaced it with a lighter spring and all is now good. Maybe you need to go the opposite direction.
I have torsion axles and shock absorbers, my trailer is like a rail car behind me.