Yes, brushpiles in any depth can be productive this time of year. Not all brushpiles will hold fish at any given time, though.
Any sonar should have no problem showing shad schools--they'll look like big globs down in the water column. For my deep fishing I generally go to places where the river channel brushes a point, then cruise in and out over the dropoff looking for fish/shad. The channel rim is a key spot for walleyes, especially, but you'll find walleyes and crappies alike suspending inside the shad schools.
On New Year's Day, we caught crappies on the channel drop where it was 54-58 feet deep. We positioned our lures anywhere from 1 to 8 feet off bottom, as that's how thick the "show" of fish was. And we also caught some from a thick brushpile on a quick-sloping point. The water was 30-40 feet deep and the brush topped out at 25-30 feet, so we just tickled the tops of the tangle, and the fish came and got 'em. (Note: we saw some hooks in and around the brush, so we knew there were some fish there.) Our one walleye came from inside a small 2-3 foot thick shad school that was right on bottom next to a 4-foot ledge that went from 34-38 feet.
Fun stuff!