From my understanding, the lemonade with P&B shakes is the ULTIMATE FAST and no longer is the MC. Anything added to the Master-Cleanse changes it.
Different set of rules apply now. You have to time when to take the shakes in relation to the lemonades. I feel that it would dissolve the full impact of what the Master-Cleanse is about- cleansing vs detoxing. You'd have to wait at least an hour between the two drinks and there are just so many hours in a day that you wouldn't be able to drink as much lemonade as is recommended.
Bentonite is a drying agent (as well as detoxer)so a lot more water will have to be drunk. (Ya might as well move your office into the bathroom!)
My ideal thought is using the P&B with the Clarkia because it could be drying out the wormies as they are dying. Whatever toxins they would emit will be taken care of then. It's also easier to schedule 3 or 4 servings of each throughout the day.