Yeah, it's all that flux that I'm betting you can take advantage of. Even a small coil (I would think just as you mentioned, orthogonically mounted, offcenter to rotation radius, and with coil ends connected) should make a field, and all it has to do is overcome air drag. I doubt a ferrite would even be needed, so the weight might be negligable in terms of throwing the ball off center of balance enough to fall out of the suspension field.