There have been tests. One dual prop tranny exists that can be retrofitted to most new boats - it is designed to go between the stringers. Main advantages - incredible hole shot, holds speed very well, backs up straight. Disadvantages: 2-props (double prop cost), does not improve top end due to drag. It is geared to turn props slowly, so you use higher pitch props than now. That increases torque and reduces drag. I've been in the test boats and they pull like a freight train. Its like adding 150 horses to the boat. It would be expensive to retrofit - like $10k plus. If you have the cash and really want a unique boat with unique capabilities - contact me and I'll get you in touch with the machinist who made it.
FWIW - they tested the boat with the gunnels awash with ballast and it still pulled out of the water to riding speed in about 200 feet. We figured 6,000 lbs water in a 205 hull.