I have A 16 foot flat bottom aluminum with a 65 johnson. Down here in the laguna madre shallow running is a must. I dont want to cut into the boat to install a tunnel unless i have to. Will more setback let me raise the motor higher? And how much setback is too much? I have a jackplate and pressure guage to work with. Also, what kind of prop will give me the best bite and least ventilation. Im talking about 6 inches of water and less. Maybe some of you racer guys can help me. Thanks