I've found that Rainbows love to eat other Rainbows. Rapala countdowns or Ultra Light Minnows and Shads in Rainbow patterns have worked pretty well for me trolled behind the boat.
The disadvantage with these lures is their maximum depth is limited. The countdown can technically go down to the bottom but that's when cast and reeled back. You can add drop shots to your line to bring these lures deeper but I'm not sure how that will impair the action.
I imagine trolling and letting your line out 100 feet or more will give you greater depth, but probably not much since these aren't crankbaits.
You could try to use a bottom bouncer with these lures, or a soft bait night crawler or leach. Similarly you could use a carolina rig set up instead of the bottom bouncer.
It's a lot of water to cover in there. Knowing the depth of the fish would help greatly. But variable depth trolling--low, mid, below surface--is another good tactic. I'm a fan of the Rapalas simply because their action often induces strikes even if they aren't at exactly the right level.
I'll probably be checking out Old Man the weekend after next and I'll let you know how it goes.