I, myself , throw one of my Ortlieb back rollers, on the check out conveyor,
so they don't automatically start loading the stuff in an unnecessary bag,
and I get a nickel off as a bag re use credit .
take them shopping even when Im not riding my bike there.
fwiw.. Cetma used the Wald hardware, and made a 'anything you can tie a rope around and lash it down to carry it' rack.