Lund fishing boat...ideas?

Restoring a Lund fishing boat (16 foot Aluminum), and wanted to install a storage hatch/container and livewell. Any ideas where I can get at least the bottom part of the box (without the door/hatch)...just need a good, light, decently strong, box. Maybe I could make one out of 1/4 plywood and fiberglass...but any other ideas. Cabelas doesn't have the size I need...dont have much actually. Thought about truck boxes...a bit too deep, and more importantly the hatch opens from the side, not the top. I am putting a deck on the boat, and want it to be flush with the deck. Again, I can buy the latch from cabelas, just not the box. Cooler might not work, because I want to be able to stand on it. Any ideas?

M