If allowed, does mean that you can trapeze off this gantry, which effectively helps drive the boat harder downwind if the conditions call for it.

But what if the gantry was styled like the Bladerider moth? http://www.bladerider.com.au/photos/fx/bladerider-fx-2.jpg

Could be seen as effectively increasing the waterline length of the hull when sitting at the back of the boat sinking the stern, and does have some buoyancy effect.