During the build of my cedar strip kayak, I cut out the hatch prior to mating the deck and the hull. During the process the deck is now flatter then the hatch cover. Because of this I can not use my original idea for securing the cover. The interior shock cord. The hatch won't sit flat enough for a seal. So, I figured I would have to use exteror straps. My question is what would be recommened to fasten the straps to a cedar deck with minimum leakage.