Flat Line Trolling for Lake Trout along the Niagara Bar

We're flat line trolling with the silver/purple, and the gold American Smelt crankbaits fishing for lake trout. We're fishing the Niagara Bar on a fairly calm day (and the bugs are out in full force). Trolling speed is about 3.2 mph and we're at about 25 feet. The crankbait are diving down about 20 feet and pulling in the trout which are holding near the bottom.