Another suggestion would be to stick to the upstream troll using heavy, and I do mean HEAVY, wire legged bottom bouncers. Trolling in rocks, nasty stuff, is about the only time I opt for a bouncer over a 3-way and bell sinker set-up and the scenario you describe is tailor-made to this application.
How to go about doing this….
Get some serious bouncers since you want to remain nearly vertical when working through this area. Allow your bouncer to wash out behind the boat due to insufficient weight and you’ll be snagged in no time flat. Keep it below the boat and things should be relatively trouble-free.
Now, off the business end you’ll be able to run a spinner rig, worm harness, floating jigheads, various snells and aberdeen or live bait hooks with leeches, my favorite for this application, crawlers, or minnows. Keep the leader lenghts down to 3′ – 4′ feet at first and experiment from there.
Slowly troll this into the current. Look for speeds less than 0.5 mph to produce best. If you already know where the fish are holding, put this offering on their noses and hover. Slide from side to side slightly as you keep your bouncer just inches above the bottom. No bite? Pull ahead slightly and kick your kicker out of gear and float back into them. Then engage the kicker and pull back through. Sooner or later they’ll feed. No doubt about it. Since you’ll be working overhead, or close to it, keep the banging etc., down to a minimum to avoid spoking thee fish. If you don’t spoke them, chances are you’ll be able to catch them with a little patience.
Awesome question. I wish more folks would ask more questions like this. I hope this helps some…