: So far I've tried sliding the looped webbing thru the slot, insert a dowel
: and pull up with a bit of silicone to seal it off.

Terry - assuming the slots in the hull aren't too much bigger than the nylon strap you're passing through the hull, a little bit of silicon should do the trick. All you need is enough to fill the gaps where the strap comes through the hull. No need for a gob on the inside.

The only advantage of a flat surface to the padeye on the inside of the hull to to spread the stress over a larger area. I toyed seriously with using dowels on the inside, but didn't want to sew loops. Sounds like you've come up with a system that works for you.

jrs