BTW, macs are fish eaters. In Cultus, their food supply are Mountain Whitefish. This is different, then the two nearby mac lakes. They feed on Kokes in those lakes. But, not in Cultus. So, a plug/lure that imitates a whitefish should do the trick.
Macs also prefer water temps, between 48 and 50 degrees. So, target your gear in the depth where you find that temp range. And they prefer structure like boulder fields, rocky outcrops, volcanic cones, ledges and drop OFFs. They like to lie in wait, and move up to ambush their prey.
And, here's a quote from "Fishing in Oregon's Cascade Lakes", by Scott Richmond.
"When presenting a lure to mackinaw, troll slowly, with just enough speed to give good action to the lure. Macks like it slow. Real slow. You wouldn't believe how slow they can like it. If Mackinaw were people, they'd be corpulent couch potatoes, the kind that would watch the same TV channel all day if the batteries died in the remote control."