see page 22 on my website. I installed a cage and use the frame, outrigger and the very edge on the bottom outside part. There it is really thick since it is a beam on the edge, but all of the stress will be on the frame attachments and the piece on the edge will be pushed up by the flapping tread so it won't take as much pounding as the front of the cage. I used 1" lag bolts there.
Tom
