I understand what you are talking about. I am considering a 13-14 ft boat that would at least start by using a Laser rig. I have several rigs, boards and rudders in my garage and attic. The cost of the boat goes down drastically if you can use existing rig, rudders and dagger board.

I am looking at tunnel hull boats, like the Laser Vortex or Hobie Bravo. I have discovered these are not catamarans, in the classic sense. The water flow is different. They are based on 70's International Moth's. The Moth at 11 ft and very light would match your Opti. If I can find plans I will pass them on. The Tunnel hull is considered a dinghy by Yacht clubs and easily accepted.

I will write a more complete post, when I find more but I will tell you what I know about the tunnel hulls. The Tunnel Hull looks like a catamaran and sails ~like one but doesn't work like one. Water flows around each catamaran hull independently. In tunnel hulls the water is one flow path. The water is forced between the hulls and the passage gets smaller toward the stern creating lift. At high speeds, it planes. At low speed it works like a cat. It is always very stable. One reason I think the modern designs are so slow, is they are heavy. The Laser Vortex and Hobie Bravo weigh 200-250 lbs. The Moths were ~ 40-50 lbs