Even if you found it preparing the fiberglass properly seems like a miserable job. Then applying it, then dealing with edges and holes. Seems like a bad idea to me.
Putting down some plywood over the glass would be a lot easier and probably last longer, be easier to repair I doubt if it would be much more money as the cost is in the veneer anyway.
You can buy it at Jamestown Distributors at only 1/4" thick..