RE: Peel Ply techniques
The way I've done the peel ply skin hinges, the peel ply (dacron/nylon fabric) goes between the outer glass (or carbon, whatever) layers and the core material. The epoxy which penetrates the peel ply acts like a million tiny rivets holding the whole thing together. There is a ton of bonding area, relatively speaking.
If you think about the loads on the hinge, you can break them down into shear and tension loads. In shear, there's no way you're ever going to pull the hinge out with flight loads... the core material would fail first. In tension, practice peeling up a fully saturated strip of peel ply from a cured laminate. First you have to get it started... and then the forces required are still very much greater than anything a flying surface will see in use.
The trick is to scribe through the outer layers of glass/carbon/epoxy and stop just shy of the peel ply. Then scribe the inside also (need to cut the lower surface free first). Then you gently flex the hinge to fracture the epoxy along the hingeline. The more you flex, the more free the hinge becomes. I typically cut the peel ply on a bias to further reduce hinge stiffness.
Just make yourself a test article like Mike James did... I think you'll be sold. He used Kevlar, I believe, but the principle is no different.
-David