I would start with a 17 pitch also. I use a 13.2X17P SST prop on a 16ft glass V hull. With 3 adults, fishing gear, coolers, 12gal of fuel, and other stuff, I can run 5200rpm@36/37 mph(gps). I still want to try a 15p, but Im still looking for a used one to try.
Without WOT rpm, and mph, with your normal load, and of course type of boat, its hard to say.