My F250 [see sig] has about two fingers clearance between the spring and bump stops. I approached a well respected spring shop about getting 'hi lift' springs made for it, and his reply was I would be wasting my money. From what he said the problem is not the lack of clearance, it is a either too stiff shock, the ten ply tires, or both. IIRC he recommended an 8 ply, 6 ply sidewall, as a better riding tire, along with 'weaker' shocks.
Is he right??...I don't know. I am not going to get rid of my almost new/expensive 10 ply tires to find out....and the shocks I installed were gas filled and now that they are used I cannot return them, so they are staying on the truck. I have thought about removing some leafs and using air bags to gain some soft ride, but probably will leave it as it is now. The Timbren bump stops sound interesting, something I may install once warm weather returns.