Given the uncertainty about the thickness of the extra glass in the bow section, I wonder how this might work:
http://www.go2marine.com/product/387757F/sea-dog-eye-nuts-stainless.html
Using the one designed for a 3/8" bolt (part # 228738), I could drill a single hole in the desired location (I would imagine about 6-8" down from the deck), measure the length and get a SS bolt and a few washers to fit. I wonder, though, if it would stay tight once threaded on. Do you think it would help this if I added a lock washer on the near the head of the bolt on the inside, perhaps paired with some Loctite on the threads outside?
The eye itself on this product is smaller (1") than most, but enough to get a snaphook onto, I think.