I think minimum for CAMS is 7 point. (2 behind drivers seats, 2 on diagonals to that to go into the rear, 2 below the dash, and there has to be at least one diagonal in the back half of it between two of the main legs, there's a whole set of diagrams in the CAMS manual) IIRC, it's between 44-50mm diameter 2.5mm thick for main parts, and 38-48mm diameter 2.2mm thick for cross bracing. I could be talking shit, but it's around that. Get a CAMS booklet if you're considering that route.
