I agree with finding the bait but don't rule out the bait being shallow....
What i'm dealing with now is the fish are really not relating to structure and that makes it hard to target crappie but yes find the bait and fish at the depth they are or just below.....
Spidering has definitely worked best for me as of late....
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Spider rigging was going to be my suggestion. Use your finder to locate bait balls and starting depths. Then use spider rigging with 6-8 rods to pin them down as to best depth and locations.. Once you locate them fish for them using the method you prefer if you don't like spider rigging.
I spent Thursday doing this. I found them in water as shallow as 15' and as deep as 53 '. The bait balls were between 2-3' higher than the crappie. The crappie were all suspended around 50% of the water depth. So in 50' of water they were suspended around 20'-25'.
The water temperature was 48 degrees. I did not find many crappie over bps nor under the bridges. They were near the bridges but 30'-40' out from the bridges.
I marked them with my finder and then used spider rigging along the path of the bait balls.
Bite was very slow.