RE: Please help
If I understand you correctly thats 2 1/2 pounds per sqare inch, you can probably get 5 times that vacuum bagging it.
I made a 2 Meter wing with balsa, white foam, and epoxy, using weights in the early '80s, I broke the wing up when I got out of soaring, I found that maybe 5% of the foam was glued to the core, yet it had never failed in flight with what in those days where quite hard launches for several years.