I have a 24 foot class C E-350 ford based motorhome. On good roads it rides great. Humps are handled with ease. However, pavement strips feel like 6 inch dropoffs. I just drove from south Florida ...
Best ya can do is weigh your rig and then adjust air pressure for the weight. The 75-80 psi may just be too much for what is needed. I dropped down 5-7 psi on my aspect and it made a difference we only weigh about 13K loaded so dont need the high pressure on the placard. Give it a try. Also run the airbags at about 55psi lifts the rear end up a bit and does actually smooth the ride some.