I had a Kadet Senorita (the 25 sized Kadet) that I bashed, took all dihedral out, cut in 1/3 cord ailerons, and shoe horned a YS63 up front. I called it Kadet Can Do 3D 2. I won't bother describing flight performace in detail, but I'm convinced it went straight up as fast as it did in level flight.

Anyway, my ailerons were larger than yours (1/3 chord), and I had about 30 degrees of throw. But I'd think anything around 10-15 degrees would be enough for normal flight with your 1/8 chord ailerons.

If you are sensitive to yaw coupling, you will want to setup a aileron differential or a rudder mix to fix. My Kadet had a pretty strong adverse yaw from ailerons. I fixed mine with a rudder mix for axial aileron only rolls. I can't remember exactly, but I think the rudder mix was pretty steep, like around 30%-40%.

Cheers.