[DonRotolo]

The rules are pretty clear that you must use wood that is 5" x 3/4 thick. A notch that brings the wood to <5" violates the rule.

That being said, remember that the bumpers can be as low as 2" off the ground, so if the top of your bumper is > 7" from the ground perhaps you can lower it/them.

Regretfully, if your design will not function when a legal bumper is in place, you are somewhat out-of-luck, and it becomes a lesson-learned for next year: Read the rules carefully.