I'll bet after you do all that work there won't be enough space to store a six pack on either side. The way I look at it if there was room, they probably would have access ports already there.
What you could do is take a small drill bit - maybe 3/16 - 1/4" or thereabouts and drill a test hole. Just through the glass far enough to see if it is foam filled - I kinda' doubt it. Patch it back up with Marine Tex if that's as far as you decide to go.
If you decide to continue please post some pics of the progress - be interesting to see the end results.
Thought I'd verify that you should drill from the seat top inside the boat - not through the exterior hull. You just never know - .
