You mean like this
What works well is instead of using just the ball head, use the manfrotto video adapter that can slide with the ball head on top. Or position the camera further out along the aluminium. You just have to be careful of flexure in the aluminium bar then.
Except that Mike is imaging at prime focus.
But Mike you could try mounting the weights to the end of the Aluminium bar. Yours is thick enough and as long enough.