I don't Crappie fish, but have fished SML 47 years, and still going.
All during those years, I have always heard that the farther up the Roanoke River arm and the Blackwater arm of the lake, the Crappie fishing gets better.
From what I've heard, most Crappie are caught near the backs of creek, off docks, laydowns and submerged brushpiles (if you can find the brushpiles.).
It's a bit of a run either way, but going farther up the River or Blackwater, may get you some better action.
Believe it or not, in all the years fishing SML, I have never caught a Crappie, not even by accident.
Wish I could help you more, but that's about the limit of my Crappie expertise.