My cams are plastic. I cannot conceive of how a bug with the maximum load you could reasonably put in it, could even move if the cams are properly locked on the rack. They'd have to break first. There has got to be something wrong. Could you take a picture or something showing how you have it set up and how you have it locked into place? I had mine loaded to the gills yesterday and it was locked on tight on the rack.

Like I said, my chainstays are 5mm shorter than yours and I have plenty of clearance with feet that are not much smaller. Same rack, same bag.

J.