If anyone were to ask me, and they probably won't, then I would reply that you guys shouldn't go below 130 kg all-up weight. It may actually be wise to set the min weight at 140 kg. Reason, Builders want to be able to produce hulls relatively cheaply and 20 foot hulls with such a rig will take alot of load. Producing such hulls below 35 kg per hull may be a bit much to ask. Especially if you want to the rig to allow for a jib. I know that the jib has gotten a pretty bad reputation over the years but that is undeserved, especially for distance races the jib is a booster that you want to have on board.

Also I wouldn't decide for a very big sail area. Look more to the balance you are trying to achieve. Sometimes less is definately more. Pardon my example but the F16 has the SAME upwind area as the Hobie 16 design and shares even its hull length, still it is a huge amount faster. The trick is all in optimizing the RATIO'S and not in just supersizing the specs. In this respect, going smaller may actually be faster. This holds for the hull length as well.

Think along the lines of

20 ft length (although I think 19 foot would be faster because of better ratio wetted surface to prismatic ratio)
10 ft wide
9.5 mtr tall mast (less overall weight means less volume in the bows so don't make the mast taller)
18 sq. mtr. mainsail with max 9.1 mtr luff (aspect ratio 4.5 more than F20, F18 and tornado, less than A-cat)
5 sq. mtr. jib sail with about 6 mtr luff (otherwise the bridles will be too far forward, bad for loads and dive recovery)
21 sq. mtr. spinnaker with a long luff (Narrow spis are fast much more than when keeping stacking area in there)

Maybe even get 22 sq. mtr. spi is you want to come out at 45 sq. mtr. total area.

Wouter