"The outriggers are purely for stability (motor cruiser and down wind sailing) and I don't see why I can't lower the rear of the outriggers to add extra buoyancy to the stern where I need it."
Beau - This statement seems at odds with the theory of the boat. If the outriggers are for stability and you are adding blocks to their sterns to provide buoyancy they are now buoyancy devices and will definitely start adding their own drag to the system. In other words whatever drag reduction you are trying to get on the main hull will be transferred to the outriggers.
I love your concept but something has gone wrong from theory to practice and I am guessing it has a lot to do with weight and balance.
In my humble opinion this wedge shaped flat bottom boat wants to behave "like" a planing hull and if it is really light it will without the need of an engine
to push it up on plane.
I am guessing that it's getting so heavy now that it won't. The inelegant solution seems to be adding hp until it planes. The efficiencies you predicted in my opinion have to come from somewhere unless we are bending the universe.
If you add big engines now you have to think about tankage for the thirstier engines. More tankage more weight - every designer
since the begining of time has chased this demon. You will then reach the conclusion that you have a displacement
boat, you will throw in a diesel
mill for efficiency and live with 8-9 knots.
Get the weight out and get it balanced.
Just speaking out loud here.