For what you suggest to work the camber change would have to take place over the entire span.

Most pylon racing planes have very short aileron span, 8-10 " is common. If you used them as flaperons, what is the rest of the wing doing?

I'm sure someone could come up with a design for the fastest turning plane, but fitting it into an existing set of racing rules would be hard and it might be at a disadvantge compared to other designs that are optimized for a given set of rules. Just depends on what your after.

If you look at Q40 planes and watch them fly, I believe they are as optimized as they can get, while still meeting all the class rules.