I bought the wrong lock mount for smaller u-locks and thought before sending back an open pack that will be thrown away by rain forest company - why not print 2-3 bits and get a mount out of it. I've added the openscad files so you can change some bits, but be careful, it's not super duper relative.

Update: the klickfix thing fits, I just had problems sliding it over the metal bits. Anywho, if you like 3d printing and don't want to cut that beautiful red sleeving, then print this and it will slide over the sleeve just fine.