I am worried if water gets under the skin it will seep through the screw holes and on the edge where the top meets the side.
I think worrying about water getting under the skin is a good thing. At the very least––it's my opinion––that the wood should be soaked with "the mix". Me? I use thin Raka epoxy.
On my first build, I fiberglassed the edges with home-cut bias tape. I think it was overkill since the roof was glued to blocking between the spars.
But if you're concerned about it... I'd do it. You've got a lot of time and money into that good-looking build. Here's a link on cutting bias fiberglass tape (so it rolls over the edge easier):
http://www.tnttt.com/viewtopic.php?t=34887&p=633840Most builders attach the edges of the aluminum to the cabin by screwing down trim with stainless screws. Dry fit the trim and then reapply with a bead of sealant. I use countersunk flathead screws under the galley hinge.
Tony