Plywood core in hatches

[Scott]

Need some help/guidance....

The 53" x 31" sheet of plywood to recore the fuel hatch......I put holes in it to allow the Fairing/bonding compound to ooze through and coated with resin.....

The 1/2" plywood has a slight cup or bow in it now (I even placed cinder blocks on it to stop it from cupping too much)....

Do I dare use this in the deck??? I'm concerned that it will cause the skin to either cup or have a crown in it ( depending on how I put the plywood in the skin...cup up or cup down ) I dont want to risk losing the skin...