i'll take the position that v hulls are not slower than rounded or flat hulls. in fact it is possible that there are conditions that a v hull would be faster.
the v hull is preferable in rough conditions because when you land the jumps the hull cuts right in rather than pounding.
when a v hull leans over you have a planning surface, and will just keep building speed.
in triangle racing the beats are important so dagger boards are preferred by most designers. a hole in the bottom of the hull is required for that which creates drag. designers live with the drag because the advantage gained on the beat is worth the cost of a hole in the hull.
if you could figure out a way to design a v hulled boat that was at the top mark in good shape you would have a competitive cat since you would at least be able to hold your own if not pull away on the downwind. they say it can't be done, but the are stories of the gcat 20 hanging with the tornado upwind.
it is job to develop a new design. got lots of time, experience, money, and dependable testing conditions?