[Kevin Selavko]

Our team was investigating pneumatic springs, similar to what Eric suggested, but partially filling the piston itself instead of a separate tank, then having a latch to release all of the pressure built up in the small volume of the partially extended piston. We had very good results with this technique, but we did not use as large of a piston as you, I think ours was 1-1.5". However we chose not to use this idea because we did not want to have all that force held in place by a latch, as we have had a lot of trouble with latches in the past.