I have roughly 4" between my leaf springs and bump stops and was wondering if its a good idea to use some 3" square tubing(1/4" thick) and attach it to the axle which has 3 nice pre-drilled holes. This would result in 1" of flex til it rested upon the stock bump stops. Is this safe for pulling? Or should I go another route? I just dont want to ruin the stock bump stops.

I only pull in small town pulls, nothing too major.

You would be fine as long as it gets past the techs. I tried this and had to take them off. Tech guy said they had to be welded to the truck in order to be part of the truck. You could get a set of adjustable blocks from Tony. I have them on my truck now and when allowed to use them, they work great.