I have a hair-brained idea that I'd like to throw out and see if I could get any opinions on. I'm not sure that I'd want to try it.

What if the wood was cut out of the floor just in front of the seat in a kayak and replaced with a piece of 1/4" thick plexiglass. Then it would be fiberglassed over like usual. This would only work on a boat with a flat bottom. If you wanted to see under the water, you could just pull the spray-skirt off and check out the fish. You'd have your own glass bottom boat.