Please don't take this as unnecessary criticism, I dig on what you're doing. A really cool project you've got there. But in the future you may want to reconsider epoxy for your wood builds. There's a reason why nearly all the wooden boat guys went over to epoxy, and it sure isn't for cost savings! It simply adheres better to wood - expecially in applications where the wood is going to flex- which as a rider it will. I do 4+4 deck, 4 bottom on most of my balsa builds and never have issues with delam or solidity. That being said, there are wood/poly riders out there that have been going for years. I just had a bad experience with a balsa delam a few years ago and never looked back.