1967 Barracuda conv rear seat

Redfish, you're idea is interesting but I think a seat needs some steel framework to be stable. The seat frame Bobacuda is starting with is pretty far gone. I think if it was me I would do this:
1. Run a parts wanted ad in FABO and Ebay.
2. Reproduce the rusted sections piece by piece using steel sheet metal strips and a MIG welder.
3. Obtain a good frame for a non convertible car and do what is necessary to duplicate your rusty piece. Maybe start with a 67-69 notch back rear seat laid alongside your existing frame. Take careful measurements, slice and dice, section, add metal and weld as needed. I know I could do this if I had the pieces on hand.