Distance between truck bumper and 5th wheel? Anderson Hitch

The "physics" is pretty easy. If you had a 156" wheelbase and 2000# pin weight the difference at the front wheels is 116#. That's +77 with the ball forward and -39 with the ball behind the axle. I highly doubt anyone would feel the difference driving. (Whether or not there's a front seat passenger makes more difference on the front axle weight.)