A hole, as small as possible- provided it doesn't get gummed up to easily - in one of the port covers would work fine and not allow much water in. The only time it would even be a potential concern is if you spent a long time with one hull in the water sideways (can't right it). I think keeping it simple here would be the best idea. But then again, now that I think of it, he said this boat doesn't have any ports. How is that possible? I would put some in then behind the front beam. But he also said the hulls are very rounded. who knows. I bet if you tested the hulls you might find that there is an unintentional leak which air can escape from anyway.