The problem I saw with using the fiberglass sheet, was how the heck do you recess it into the wing so that it sat flush. I attempted to use the G.P. Electric Razor plane on some scrap material, but it just didn't seem to do the trick. I couldn't keep a consistant depth or straight line.

I decided to make a special sanding block, the exact width (1 3/8") of the size of the hinge. I then clamped a board to the TE of the aileron that lined up even with the rear edge of line I had marked on the aileron.

I carefully ran my custom sanding block along the guide back and forth. It took a little time and was a little tricky on the edges, but I was able to get a pretty consistant .010 depth recess the exact size of the hinge I planned to use.