I have small light 24 on E450 and looking at the way it sits, I don't think I want to change anything. It certainly does not ride high in the rear. Ride is not extremely rough. It's not that great on poorly paved surfaces, but tolerable. There are some terrible roads which would give a poor ride on almost anything. On smoother roads (majority) it is fine. For me the handling was a far bigger concern than the ride.
If I was to address the ride, I'd probably start with the bushings in the rear. Something to reduce transmitted harshness. Also rolling around with 20 PSI needless extra air pressure in the front tires degrades ride. But I think the front suspension is better isolated from a ride standpoint than the rear.