[MrBasse]

Yes it is fine to have your bumpers extend over or hang below your frame as long as they are within the window of 2-10" from the floor. (R22)

The gap where the wheels are would have to be covered with bumpers because they are within 8" of a corner. (R26)

Basically use the corner of the robot as you frame perimeter. The inner frame doesn't count as your actual frame perimeter. The extensions where the wheels are housed is a part of your frame.