RE: Why Glass?
i wonder how many of these died in the wool monocoters have actually finished a plane in glass and paint? a glass and minwax polycrylic combo is far lighter than monocote, monocote is what, 3 0z?, per square yard? 0.5 or 0.75 oz cloth and water based polycrylic will blow that away. adding latex paint doesn't add much more but if you use glow power the clearcoat will add weight.
i spend most of my time building classic pattern planes these days. my current project (fully glassed and painted) looks to be finishing up at 7.5 lbs or less. perfect for a ballistic classic pattern plane.