Adding setback on a performance tunnel hull is common. The weight of the outboard changes the boat balance especially with the motor trimmed out and wind or a wave cause the bow to lift. What if you moved the engine position to inside the boat and ran a drive shaft from it thru the bottom of the tunnel and thru the gearcase of the outboard. You could run a larger engine. The weight of the engine being in the front portion of the boat should improve the boat balance. Being a tunnel the driveshaft will likely be above the water with the boat at speed. The idea of having a long drive shaft extended out the transom was successfully done on large offshore style hulls. I have not seen this idea on a tunnel.
https://www.youtube.com/watch?v=rDHuXEnDXnM
