A good place to start would be Charlie Walbridge's book on fiberglass boat construction.

The concept of a flatwater squirt boat is a bit odd. I would guess that unless you are careless enough to try vertical moves in water that's too shallow for the boat you could get away with a much lighter layup than a boat intended for whitewater. For a benchmark, see what layups New Wave offers on their boats, which are definitely intended for whitewater. I don't think their web site has their layups any more, but it does have the contact information so that you can ask them about their options. If I remember correctly, their basic layup was something like a 6 layer FG hull with a 2 or 3 layer deck.