[FrankJ]

It is a bit of a stretch to say R8 prohibits yellow on a robot. Unless it gets interpreted to be a specific effort to interfere. I would ask Q&A to be sure though. It will take a little work to phrase the question in such a way that you get a useful answer since GDC tries to stay away from specific judgements.

On the other hand you do not want your alliance partner trying to pick up your robot & stacking it during autonomous. (There are no rules that prohibit this) & it is not likely an opposing alliance robot will even see you bumpers with its camera.