I am surprised that no one has posted the length from the centerline of the 5th wheel pin to the rear of the 5.0.
Call it ~20'+10" center of kingpin to back of bumper, add 6" to back of spare (I didn't use a plumb-bob for exactitude ).
That's a 'fixed' horizontal dimension, it doesn't change when you move the pinbox from "Standard" to "Extended" position, which refers to a vertical adjustment.