Money in the bank that a big ol flathead is in there somewhere. You out to noodle one outta there next summer...:D
I do think at some point if there is enough bait around to hold some decent numbers of bass and its not that far from the main river then some crappie have to come up in there at some point. Might be a killer spot for winter if its deep as you say. You would need a 16 ft jig pole to get way back in there. Keep tryin, are there any more brush piles or stumps around that you fish.