I just made full rings out of 0.32 2024 T3 aluminum, 5" OD and 3 1/2" ID, and glued them to the fabric on the inside of the existing inspection holes with Poly-Tak. I removed the spring clip from the Spruce covers and drilled four holes in each cover and each ring for #6 PK screws using a steel drill guide I made so everything matches. Now, for them to come off, the covers will need to break the Poly-Tak bond and pull the inside aluminum ring through the fabric. It's a bit more work than the other methods, but I seriously doubt one will ever come off! And they're a hell of a lot easier to take off than the ones with spring clips. Did I mention I hate spring clips?