Building a Glass Bottom Boat

[Lakegeezer]

Looking for experience or ideas about how to build a small glass bottom boat. The goal is more effective weed watching for milfoil. The thinking so far is to find a junker 14' rowboat or large bottom kayak/canoe, cut a hole and use marine bonding caulk to add a Plexiglas plate over the bottom of the hole. I'm a bit concerned how scratches in the Plexiglas will reduce visibility, but would rather not work with plate glass. What would you do?