I've tried all sorts of things to get the bolt out in this situation. Sometimes I try to save the bushings, but more often I do not anymore. I've used pullers, impact guns, cheater bars, BFH, air hammers and the like all to mixed success. If it is not rusted really bad, you can usually get it out, but if it's rusted bad.... you're better off replacing it.
Last time I messed with springs was on my F-150. I had to replace the rear spring hangers and I wanted to upgrade my leafs to F-250 custom built packs. So I didn't even bother, if a bolt gave me too much trouble getting out, the grinder with a zip disk whacked it off. Then I used a propane torch to melt the rubber bushing enough to dig it out (you don't want to use a lot of heat around a leaf spring, it'll damage the temper). Got a new bushing set from Summit Racing and was good to go. When I put the new bolts in, I use a liberal coating of either never-seize or wheel bearing grease to keep them from freezing in the sleeve again. Too bad they don't make greaseable sleeves like some of the Jeeps have....