I missed that...and another opportunity to use Stank's breasty modification of my moment diagram...I gotta find that.

You don't lose any righting moment with the line there. You, the line, the boat are one fixed assembly in the righting moment equation. You can attach the line to the mast base and still get the same righting moment if you can get your body in the same position as with the line over the hull....the lower the rope attachment point, the harder it is to hold on to but it won't affect the physics required to get the boat back to pointy side up.