You didn't say where on Lake Cumberland you are going and Cumberland is a BIG lake. I will just tell you that I have been catching nice crappie 20 to 22 ft deep on submerged brush in 25-30 ft of water and the deeper trees around the lakeshore. With the water falling, thousands (literally) of trees are being revealed around the banks and in the creeks. You just need to search the deeper ones. Also, with the cooler temps (especially at night), crappie should start biting much shallower. If you are coming in a couple of weeks, I wouldn't be afraid to try them 10 to 15 ft deep around the trees. I've been having my best luck on Bobby Garland jigs (chartreuse or pink) tipped with minnows, but tipping the jigs with crappie nibbles will probably do just as well.