The easiest things you have control over are tire pressure and tire brand. All the E450's I have had came with Michelin tires, which is known for a smooth ride and easy to balance. The main thing is tire pressure. You don't need 80 psi in the rears unless you're at the max rear allowable weight. If you have a 32' coach, you might be there. If it's a 23' you probably are 2,000lbs under RAWR, and could get by with quite a bit less psi. As many have said, weigh the coach, and go to Michelin's web site for psi guides that will tell you what pressure to run for your weight. On my 32' coach, just going from 80 to 75 psi is quite noticeable.
Having said that, it's still going to ride hard cause it's a crude truck with a lightweight hollow box on the rear filled with every rattily, banging device known to man.
CT51