Suspended/river channel Reservoir crappie

Spent my holiday break scouring the brush piles of central Kansas reservoirs. Managed about 20-50 fish/trip, and kept about a dozen for the table. My question for those in the know is what structure or lake features should I key in on in search of suspended or river channel crappie schools? I have no issue finding the piles and fish in late fall/winter but for the life of me struggle to find the suspended fish in the channels. Can locate mountains of shad but ive spent some serious time behind the wheel scanning for crappie with no luck. Not looking for spots just advice on what to look for to start a search.

I'm no expert but they just might not be there. We fish Kirwin until it ices up and don't really find enough we can concentrate on in the channel. We find more staged near the brush piles, ridge edges, and the dam. Some are even pretty shallow.

I usually find crappie, this time of year, under the shad schools suspended at 12-15ft in about 30+ ft of water. I usually don't see anything on the fish finder except shad. I drop a jig through the shad school and find fish. Not only crappie. I often will catch bass too. Even occasionally a channel cat. It's open water fishing, on Hillsdale, which has a lot of standing timber