OK, I understand. If you put that at the leading edge, you are going to have a spoiler effect and loose all laminar flow on the bottom surface. You will have to slot the front of the flap to make sure that you maintain some laminar flow!

I know you already know this. One question that I do have, how are you going to maintain strength at the hinge line of the flap. If you are flying at any reasonable speed, you are going to have problems with the servo or flap. You will be moving a lot of air!