A multi champion crew chief I knew said their cars cleared weight without the driver that the rule included the driver. So not all of em are on the edge.
I don't think RB's problems are weight releated at all. He's lost the weight here and there. It's a good setup and making the right moves at the right times.. I watched Bob Kinser, Dick Gaines and Shane Cottle whoop too many asses for that to be a huge factor.