The expandable safety tether is a good idea. Instead of using regular line or webbing as a tether, elastic is slipped inside tubular webbing to form an expandable tether which hooks directly from the harness to the boat. The expandable tether stretches for movement (from 1 to 2 meters) and does not hang down where it gets in the way.
This finished Expandable Single Tether features: 2 Wichard snap hooks.