I have a D lock and a cable, the cable is coiled with each end going through a leg of the U-Lock, it is mounted on the downtube, but with the mount turned out to the side, so that it goes back, overlapping the rear wheel. The Cant brake sits inside the D of the d-lock, and I have a little velcro strap that holds the cable, and D-Lock tight against the seatstay, so there is no rattling or movement back there. The lock sits half behind my pannier when the pannier is mounted.

This way I don't lose a water bottle cage, but still have the lock mounted to the frame.

Not sure if you can see it in the attached photo, most of the lock is hidden behind the pannier.

San Remo 1.jpg