Don't think your sole will last ol'sock.
As you know, the manufacturer of the bamboo wood product that you used, specifically states in their product literature to never ever use it in a damp environment. You can try to seal it up with all the materials you mention, but it is still going to swell up and look like hell in a short number of years. Sorry to be so negative, but I did read what the manufacturer clearly states in their product manual.In your link, I noticed that your cockpit drain pipes are held in place with single metal clamps. Suggestion - use double all stainless steel clamps on these fittings just to be sure. You won't pass a survey unless you do.