I have the RRS L-Bracket for the D600 and D7000. The side port access for a cable release presents the same problem on both cameras when the body is mounted vertically.
The solution is to attach the L-bracket in a manner that allows space for your cable release. The designs of the RRS and Kirk L-brackets feature a slot for the attachment screw so you can position the bracket as needed.
When you mount your camera in the quick release, you need to position it so the cable connection is not bent or contorted. That is a little off center.