Couldn't you simply drill a few holes horizontally in your FRP reinforcement piece between the shock towers, add some wire wing mounts, bend a wire and mount a wing to that? You could even slip the wing wires into the existing screw holes in the body's wing mount "posts", perhaps.
Here's sort of what I'm describing:
The Optima doesn't have a wing, but I used this idea to install one on one of mine:
