Just some suggestions
- Make rowing more of the primary lifts, bentover rows/cable/db etc, and pull-ups/pulldowns secondary. The rowing lifts will incorporate more muscles and if you are trying to get your overall back to grow this is a better route then trying to target (that comes later)
- Traps, shrugs, try shrugging the weight up and hold and squeeze the muscle on top, hold it for 3-5 seconds, you won't need as much weight. Once they start getting stronger throw in some heavy weeks .
- Lower Back? other then DLs I don't see any lower back, GMs, Hypers, Romanian DLS and pull-throughs are a few choices.
Check out the stickies in the PowerLifting/strongman forum, there are some good articles that will definitely help you out. Remember the Back is a big muscle group, do you train your chest or arms more and harder?
Just some ideas, hope it helps