Well with your kickback stopper removed you won't be having that problem again. You'll just have to watch to make sure you don't overextend the leaf spring. I don't think dog legged shackles will help. Once the centerpin hits the frame it's going to lever against the hanger again. In which case it would have been better to replace both hangers with ones that are a lot stronger. Another option would be to go with a shackle relocation kit. A third option would be to run limiting straps on your axle.
Those are good points. To avoid breaking the hanger in the same way the lever action has to avoided and this means avoiding the boomerang shackles.
A shackle relocation would definitely work but it might cause other handling and trail performance changes that I might not like. Oh, and one of my wheeling buddies said I should just convert the front to a link suspension, but that would be much more costly.
The two options I'm seriously considering are:
1) limit the rearward shackle movement from the front with some lengths of chain or cable, the chain would go from the bumper to near the lower end of the shackle, or
2) weld an extension on the rear side of the shackle that will stop the swing of the shackle, this is the same general idea as a boomerang shackle but it would be placed near the lower end of the shackle so that it would not cause the lever action that a boomerang shackle would allow.
Both options would be unusual but in the end I'm more interested in having a very reliable Jeep than one that looks "normal".