Re: Am I an 'operator' at anchor?
You can always be charged under the federal law -- so the state law should be viewed as possibly worse (harsher) but not as a lower burden. I have zero confidence that "at anchor" excepts you from the BUI laws in most places (I appreciate the state laws quoted above). In PA DUI is "operation and control" of the vehicle. Begin by recognizing that that law has been applied to bicycles! Next note that "operation and control" has been interpreted to mean operation OR control. So think: you could drive the car" not "you did drive the car". With that in mind, and the same courts interpreting the law, I figure there is no way you are immune at anchor.
.02 (and certainly not legal advice)
Come not here if you have already spent the best of yourself