Hey Sail, Where I come from you are taking a pretty foolproof system and trading it for leak prone weaker portlights. If you are just trying to increase ventilation, you might consider installing deck
hatches and/or dorades which don't have quite as many leak problems as a rule. As with any project on a boat, as long as you have sufficient M&M's go for it.
Regards,
Red
M&M's = motivation and money
