I was planning to use these:
http://www.mcmaster.com/#98480a562/=u6jsf0
Also pretty expensive, but 1/2 in diameter. I'll definitely take a closer look at yours though. Could you possibly clarify your point about the attachment points? We use a 6 wheel drivetrain, so for the sides the attachment points would be between the middle wheel and the wheel on either side, while the front and back attachment points would be as far to either side as the frame allows. Thanks for your feedback by the way! And I'll definitely force my teamates to run some drills on bumper changing
