Glassing the hull will not add a lot of weight when done correctly. Lay the cloth (something around 1oz cloth) out on the hull and then spread the epoxy over the glass and push it in. I actually use a popsicle stick for this. When done scrape away as much of the excess epoxy as possible. This will reinforce the hull and provide a waterproof layer.

Or

Just use a coat of epoxy mixture over the bare wood to seal the wood. Adds less weight but no reinforcing, just the waterproof coating.

Ryan