8 Inch rule?????

[neal]

So the frame has to be 8 inches? I'm sorry, it's just that we can't find the exact answer anywhere.

If the plywood has to be 8 inches, I'm pretty sure there's a rule that all of the plywood has to be supported by the frame. But I just want to double check it.

This is our case: Frame is 27 x 37, the 27 inches side has 6 inches of frame on each side and 15 inches of opening in the middle for the ball. Would we have to change both of those 6 inches to 8 inches? If so, that would kinda suck - we'd only have about 11 inches of opening.