08 Silverado Crew Cab Box?

These are the max measurements I have for the box. Im planning on putting two 12" Kicker CVTs in it which will fire up. If someone could draw up some plans for this box with all of the wood measurements and volume, that would be more than great. If you can make the box sit lower to the floor, that would also be great. If this box is a little small for these subs, I will put in some polyfill.

Thank you very much and sorry about the big picture.

Chevyman