[EricH]

I think you'll have more trouble with R21G than with R21B. Your bumpers are supposed to be attached to the Frame Perimeter. If your mounts are part of the bumpers, I would not consider your bumpers to be constructed in compliance with R21 (in total).

Of course, the "easy" way around this would be to build the mounts onto the robot... but that changes what your Frame Perimeter is and lengthens it.