Ok, so allow me to take this to an extreme. I start off with normal pool noodles. I then compress them repeatedly so they are no longer 2.5" in diameter. I then use them to create a set of bumpers that are significantly smaller than those used by most teams. This gives me roughly one more inch of robot length than a typical competitor. In your reading of the rules this would be allowed.
regardless,
Rule r27 and diagram 4-5 is where I am seeing the issues here.
it defines the width of bumper material as 2.5" around the corner.