There is NO such thing as anchor for brushpiles if preferable.
I know not all have great skill at working the trolling motor, and it takes a lot of practice. However, only people who make effort to put out brushpiles truly know how much hard work it is. Please don't use anchor if you can help it. Learn and learn and practice and practice some more of how to properly use your trolling motor to fish for crappies over brushpiles.
Fishing brushpiles is 95% directly on top of the brushpiles. There are a few occasions where it is more productive by throwing a marker buoy to mark the brushpile then situate the boat away from it to cast in, let the jig fall across it. Otherwise, it is mostly effective if your boat is actually on top of the brushpile where you can actually see it on your graph.
With that being said, typical anchor is usually 50' away from the marked brushpile. Any light wind would eventually drift your boat off of the mark. Hence, many people tend to drop the anchor right next to the brushpile if not actually onto it. Dragging the anchor intentionally or unintentionally will ruin such brushpile in which someone was kind enough to make the effort to sink.
For myself, I don't even use high poundage braided line because I would rather loosing a jig any day then to even break off a little branch of any brushpile.
Remember, locating the fish is 90% of the work of catching. If a brushpile is holding fish, cherish it because next time out, that brushpile might no longer be there to hold any fish!