I'm curious if you've tried your method yet. I might be making some composite wings soon, and need to make the wing plugs. I'm not sure if removing the glass is going to give you a workable surface for plug surface finishing...

I was planning on building a normal wing set with the typical foam/balsa sheeting, then glass. Instead of using the typical 3/4 oz cloth, I'd probably use a couple of layers of 2 oz, to get the surface harder...