boost tab question

I made aileron boost tabs for a gas pattern airplane that seems to have a sluggish roll rate. The tabs turned out to be 15% of the area of the barn door ailerons. Cannot wait to test the concept but it is too cold to fly.

I am guessing that no convenient method exists to measure servo loads and verify effectiveness.

When you are uncertain about the geometry where in the slipstream should the tab be for initial testing? I would guess that a few degrees of positive into the slipstream when the aileron is deflected would avoid oscillations or flutter due to linkage slop.

Bill