It sounds like you've done some good experiments and learned a lot from the plane. But I still think all the washout comments you got were right on target. Full scale Cubs were manufactured with washout. Since it's a garage sale plane anyway, why not cut the ailerons about 6-12 inches from the end of the wing and re-glue them up a bit relative to the rest of the ailerons? It would be an interesting experiment.
On the other hand, I guess full scale Cubs didn't do a lot of inverted snap rolls!
Jim