score:3
Answering my own question:
Seaweed accumulation was fairly minimal at our resort on the east coast when we arrived. It got noticeably worse during the second week of our stay, and unfortunately for the hotel their seaweed-clearing tractor seemed to be out of action, so efforts to shift the deposits by hand couldn’t really deal with the volume. The hotel set up a free daily transfer for guests to a west coast beach a few miles away, where there were virtually no seaweed deposits.
Have to say though that the Crane is such a fabulous location to stay the chance of a seaweed problem would not put me off from returning.