Never read anything about Silicone shrinking.
Your latest plan is exactly what I have decided to do. I will lay lightweight Fibreglass Matte on the backside, mashed into the Silicone smeared all over the backside of the cells.
Wish I had easy access to Formica sheets. I would take a sheet, cut to just a tad under size to fit the frame, and s,ear paste wax on the Formica. Use that to lay on top of the glass matte and weight it with plastic bags of sand. It will peel up easily, without pulling the Silicone loose. Use on all the panels you ever build.
I really think we have a winner planned out. GOOD LUCK Wish my Son would get off his ass and ship my stuff down, ASAP.
In all fairness, he is VERY busy in the crappy economy, and works 14-16 hour days, 7 days a week.
I'm gonna rattle his cage, tonight.