The gantry (in my opinion) is a rule induced abberation which is NOT necessary for a successfull foiler design. In fact, there are really good reasons why it should be eliminated:
1) by allowing the hull to be a bit longer the available hull buoyancy is increased so the L/beam ratio can be increased reducing resistance and allowing the boat to achieve takeoff a bit sooner.
2) In my humble opinion, it is somewhat ugly and help creates a "contraption" appearance to some onlookers.
3) When taking off without an F-box(angle of incidence control) a gantry (and transom)drags when the boat is pitched bow up.
4) The ONLY reason for a gantry is to allow the foil footprint to be better on a boat NOT DESIGNED FOR FOILS IN THE FIRST PLACE.