I think that this would be a lot better done with epoxy. The open time alone would make it easier. Add to that the fact that it is cheaper than Gorilla Glue is only a bonus. The only thing to be careful of is that you can over-clamp epoxy and starve the joint which makes it weaker.
I prefer the System 3 epoxy and in this case, the GelMagic would suit well. It has thickeners already and is dead simple to mix up. They even sell it in a caulking tube that mixes as it comes out. (That is a bit pricey though) Do the math and see how much the glues cost per oz.
I would also think about putting a real light glass on the bottom. Maybe even down to 0.5oz cloth. Just to toughen up and prevent dings. fiberglasssupply.com has a good selection and fair pricing.
Another glue to consider would be Titebond III It is waterproof and a lot nicer to work with than the polyurethanes. I can’t say it would do as well as epoxy long term for prolonged wetting but so far people building boats have been having good success with it.
-- Woodworking shouldn't cost a fortune: http://lowbudgetwoodworker.blogspot.com/
