I've got 30% rudder mixed to my ailerons (Program Mix #1 on a 9C Futaba) and it's about right to get rid of most of the adverse yaw in a turn. I've got the older H-9 Cub, flies about the same as the PNP; you'll also want to program some differential in the ailerons (more UP travel than DOWN), that will also help keep the tail from dragging through turns.

That said, I agree with exeter and b.l.e. about just learning to use the left stick for more than just throttle. Just program the differential, and do without the mix. Playing with the rudder is half the fun of flying a Cub, and you'll be a better pilot on other planes as a benefit. Although I still have the mix in my radio, I generally use the rudder and elevator to turn my Cub floatplane, or use opposite aileron to keep the turn flat, or to sideslip in a crosswind.