I would be prepared to run a sweep pattern. That also means having someone on the other end who knows what signals to look for and how to feed you line. From your description the viz is gonna stink so you are going to probably be feeling your way along. Not to mention the current. Plus I would find a replica of the shackle and practice securing it with your lift rope with a blindfold on. Prepare for possible entanglement - two cutting devices at the ready and finally as Plmr747 said........get a good buddy! Oh, one more thought - if the conditions are bad - thumb it.