Very valid concern about disturbing muck, Bill. I THINK my bucket is OK, it has about 3" of stones in the bottom and is VERY bottom heavy (I put a life jacket on me and another on the bucket for the delivery and still had fun getting it in place).
Our duck has about 5'-6' of slack in the line; it functions as a wind sock wrt the boil. If it should coil the line enough to tighten, the duck drowns as the bucket is too heavy.