[Al Skierkiewicz]

It is my understanding that your configuration would be legal. Team Update #1 has been issued and the dimension has been clarified as ”84” (213.4cm) diameter vertical right cylindrical volume.
The bumpers are part of the robot so as to minimize damage from robot to robot physical contact.
From R07..
BUMPERS have several advantages, such as reducing damage to ROBOTS when they contact other ROBOTS or ARENA elements, and being excluded from the calculation of ROBOT weight and volume constraints specified in Rule <R11>. The BUMPER location and design have been specified so that ROBOTS will make BUMPER-to-BUMPER contact during most collisions.
Please remember that all other sections of the rules apply to your design as well. when in doubt, please form your question on the Q&A when it opens.