My only thought is that a 8" deep CP is AWFULLY small. I tried to keep mine as absolutely small as possible and still be comfortable witha tarckball, and 2 players with 7 buttons each, and the smallest depth I could come up with is 14"
Remember, you lose .75" on ALL FOUR sides having the "box" sides of the control panel, PLUS if you want an overhang on the top piece, you're losing even more space (I went with a half inch overhang, which means I lost 1.25" on each of the four sides, ok .75" on the back, and 1.25" on the other three sides)