Dave,
I cut a 4 inch length of cable roughly the same diameter as the plexi's thickness. With the canopy resting in place on the frame, I sharpee-marked on the frame the bottom edge clearance of the canopy on each side of the ear. Then, with the canopy removed, I put the cable piece under the ear, lined up with the edge line markings. This piece of cable now becomes a sort of 'bend brake' for the metal ear.
I then just bent the ear inward, just a little, so that it conformed with the plexi surface. You'll want to drop the canopy back on a time or two to check and adjust the bend. It worked like a charm for me and my sika'd canopy.