Snsmith,

The low aspect ratio spoiler you are talking about on the bottom of the wing isn't what I had in mind.

If I were you I would shorten the present aileron up to the the inboard hinge and lengthen the root trailing edge piece to take up the space. I would thin the trailing edge on the bottom by 1/32 of an inch from the wing root to the inboard end of the aileron and install a 1/32 ply split flap about 3 inches wide and as long as possible between the fuselage and the inboard end of the shortened aileron with the trailing edge of the split flap corresponding to the trailing edge of the wing. I would use 3M Book Tape for a hinge. If you don't want to mess with the wing root sheeting, so be it. Just overlap the 1/32 ply and live with the 1/32 bump in the airfoil contour at the flap hinge line! Only you will notice it on the bottom of the wing and performance won't be affected perceptably with the flap closed.

The reasons for this are that a long narrow flap is more effective and much easier to drive than a short wide one. Having the inboard end of the flap almost graze the fuselage side cuts most of the vortex that would otherwise be generated. This greatly increases the lift available from the flap and decreases the angle of attack needed at the wing tip for a given airspeed. The resultant decrease in tip angle of attack gives more tip stall margin which is what this modification was about from the beginning.