I have no experience in a situation like yours. Why not go back to the original doctor, tell him what you are trying to do, and see if the diagnosis can be changed? Perhaps he made an error?

If that doesn't work, contact your local representatives. Maybe they can help?

Ultimately I think Hrkdrivr is correct. Any prior back injuries are going to be perceived as a big issue -- especially when it comes to flying ejection seat aircraft. I am not sure if the T-34 has been fully replaced by the T-6. If not, you could go T-34s and then to C-12/T-1s to avoid the ejection seat. The problem is, you're on the outside trying to work this. And the military typically doesn't work these types of waivers for those on the outside. If you were already in the pilot pipeline when all of this happened, things would be very different.

Good luck.