I think what you are saying here is that those areas that have cores removed (post 11, the thin remaining foam areas) will be sucked outward and fail. Makes sense.
Well, sort of. Composite facing and then foam, with no composite facing on the other side will be way softer and way weaker than with a facing on the other side. It is not the end of the world, but done properly (thick enough foam, narrow enough space with foam missing) with a slow enough airplane (all of these terms are relative), it can live long. But if you are willing to go to these lengths to make it light, why are you building in fiberglass?
Fiberglass is great for folks who are going low drag first, and are willing to take a small penalty on weight. Even if you can make a holey cored fiberglass wing stay in one piece, bulging skins first trip the boundary layer from laminar to turbulent for an increment of drag, then as deflection gets bigger, it adds some more drag. So now you are a little heavy and not low drag. If you can stand that, knock yourself out... analytically first. I talked above about how to do all of this.
If you are really after low weight first and low drag second, you can go Tailwind/Falco/GP style. Wood spars, stick built ribs, plywood skins, and then a really light fiberglass skin. Generally lighter than fiberglass, nearly as low drag if profiled correctly, can be painted any color you like, and if you go to the light end of the wing loading spectrum, skip the plywood between the D-tube and drag spar, like the Buttercup.
If you are not concerned with cost and want low drag and low weight, you can build in graphite fiber. Maybe even lighter than the wooden wing and can be made as laminar as any other airplane ever built.
But it all comes back to "what are you really trying to do, and why?"
Billski