In the guitar building world, we "sticker" the wood, stack it with sticks leaving about 1/2" of space between each piece. This lets all sides of the chunk of wood react to weather changes at as close to the same rate as possible. I know this may not be easy, but is there a way that you can stack or store your ply with an air gap between each piece? Sometimes, I will just lean a long piece of wood up against the wall leaving plenty of air flow on both sides. When I do it this way, I usually only get warping in highly figured woods.....which are somewhat of a crap shoot anyway. Nicely quartered or straight grained wood only warps for me if I stack it without any air gaps. Then, if I improve my stacking, the warping goes away after a day or two. Just a thought.
So, my big brother was playing guitar and I figured I'd try it too.
- Stevie Ray Vaughan