Not saying this is ideal, but given the circumstance, hit the lateral raises from every every possible way:
DB standing, DB seated, DB Incline lateral, DB Lean-away lateral, Cable lateral (using each variation i used for DB), machine lateral, use bands, experiment with combining bands and dumbells or cables and dumbells for even more variety, you can do negatives by raising dumbells in the "L- Lateral" raise(arms bent 90 degrees) and lowering them with arms srraight. Do negatives on lateral raise machine by having partner help you raise it, then you lower it on your owwn. Play with the rotation angle of the arms. Try some static holds. Do face pulls. Make sure not to neglect the rear delts. Do the last exercise on this article (its deceptively hard even with only 10 lbs!):
As far as traps go, I think you're SOL. I have kinda shitty traps, but what I have learned is that Traps are mostly fast twitch, so they respond best to heavy weights and explosive moves; neither of which it sounds like you can do.
But just get creative on the delts. Use drop sets, various volumes, various rep ranges, etc.
I hope this helps. Read some of Thibs old articles....he has lots of cool shoulder exercises. Good luck!