If all else fails putting more lead on left side would help more than the added weight would hurt you. But others have given you good ideas. Moving the track over to gain the leftside % will affect handling. Good or bad , but will definitely affect it. But running with too little left side will affect it also. And not in a good way. You Might try a lead sheet in the seat to see what that does. or do like the indoor people do. Move a piece of lead from the seat to the left side Nerf bar. They use reinforced bars and put lots of weight on them Sometimes. If your seat is hitting the frame, preventing it from moving more to the left , I have seen people notch the seat to make it fit without binding. .