Bobberman - I was thinking the same thing. Let it ferment for a week and then use the juices. I can certainly get plenty of both roots around my property. I'm going to try it. I can't see how it would hurt anything.
Note: Burdock roots run very deep. It's easiest to dig around the plant with a spade about 10" from it. Then, go deeper with a hand-held trowel. They are best to eat in the early spring after their first year. For this purpose, I think tough roots from the biggest plants will do nicely.