Might sell the F450 and go F550 with liquid springs

If you are going F550, you might also consider a chassis cab F350 which is higher rated than the F450 pickup style and with 17s on the F350, it's probably going to be a better ride than other options. Are you running the stock suspension on your F450. My current tires ride a lot better, and I found Bilsteins shocks and are bags help. I would guess liquid springs are more similar to the air bags.