Drilling a Red Sea reefer?

[NYCTURBO]

Not sure if this is going to work but I’m willing to give it a shot. So here goes Red sea reefer 250G2 I removed the overflow weir and the standard Red Sea Plumbing. I’m looking to seal the lower holes with a piece of half-inch glass. And drill the back for ghost overflow or something similar hopefully not tempered glass. Looking for a small scrap piece of half-inch glass if anybody has one? or any better ideas to seal the lower holes. I looked for the correct size bulkheads, but I have not found any. Thanks