[Airslot]

Let me start by saying that I'm no 'glass pro...

I think what I'd do is leave all that glass intact. Cut new stringers out of 3/4 ply and glass them to the existing glass and box in what you got. She'll be stronger than new when done. You'll have to scuff the old glass pretty good, clean it up, and the you should be able to get a good bond. There will be other ideas along shortly...