The WSM is a great smoker. It is a good thing you mentioned that, because the end smoke product is much different. Even though by the time you add the ribs the surface of the brisket will be well over the 140°F temperature - a temperature that smoke is assumed will not penetrate into the meat, you will still have smoke adhesion. As long ad the surface is moist, the smoke will adhere.
If it was the Bradley I would suggest applying half the smoke at the beginning of the cook, then the rest of the smoke when you place the ribs in. With the WSM, I would wrap the brisket at some point prior to adding the ribs. Your bark should be fairly well set at that point, though it may be a little softer than ususal. Also your brisket will finish sooner, when it is wrapped.
