I epoxied a strip of 1/32" ply along the rear 4 holes up to the break in the compound curve. For the first 2 holes I went with 1/2" square pieces of 1/64" ply due to the thicker plastic there. I predrilled all my stiffener holes to prevent cured epoxy from throwing the hole off when re-drilling after the install. I did use nylon 4-40s for screws and after 30 minutes of run time on the engine there are no cracks....yet. I did see prop wash pushing in on the left side canopy during hi-throttle. Floppy thing to work with, huh.
Jack