^^ My bad. I was flashing back to an old rack that I had that attached to the AXLE for a bolt-on wheel where the axle extends past the drop out. Very sturdy. I support your skepticism of the weight bearing abilities of the normal quick release. I see the Axiom rack is a QR thing.

Even with the stronger-than-normal QRs sold in the Tubus kit, you have a pretty limited load. They say 25kg -- a lot better than the performance some of the Amazon commenters reported for the Axiom, but a lot less than it's "110 lbs" some cited as spec'd.

I do note that Tubus seems to target their seat stay adapter only to the TOP mount. Yes, it looks sturdy and better than the average P clamp. But, cycocommute, I can't tell -- are you suggesting using those for the bottom of the rack?