Ran across your post. For what its worth.
336 Canyon with twin 425XTO. Bottom painted, 3/4 fuel, 1/2 water, gen, live wells full, 4 adults in salt water
Troll 1.6-1.7 MPH at 7.5 knots at 1500 rpm
Efficient cruise - 1.1- 1.2 MPG @ 28 MPH (3500 rpm)
Top Speed - 50 MPH