I think Karl_Brogger has made some good suggestions - finer hulls, T foils (rudders), and a specialized mast-sail combination for the uni config.
The one foot wider boat comment could be most easily addressed with allowing beam insert racks - mini versions of the H17 type and removable for 2 up sailing. Would require a rule change, but that is the route I would go....
The wider boat will create havoc with more slender hulls creating immersion and lots of drag, from on the water playing with beam width, going narrower seems to make the boat better suited the 15sqm the solos are allowed with earlier hull lift off countered by the very effective downhauls when the wind speed goes up. The trouble with lots of downhaul is again the sail becomes very draggy and the boat tends to slow. Lots of balancing one thing with another I'm afraid.
Weight is not really such an issue.
