[BBray_T1296]

If the bumpers are true-to-drawing, The would be illegal as the corners in front/back are not protected. Like jblay said, as long as they are entirely within 2-10" of height, it does not matter what they are mounted to, provided that the mount is sturdy enough to take the impact of robots.

If you are planning high bumpers, I would personally advise against doing so if at all possible. This is due to the phenomenon where in a pushing match, the robot with the high bumpers tends to ride up on top of the bumpers of the low bumper robot, transferring a small but significant amount of your weight to their wheels, giving them more traction and yourself less (f=uN)