Jon, you are forgetting that ackermann steering can also be achieved by pointing the steer knuckles towards or away from the centerline of the car. I'm kinda new to the whole ackermann thing, but from what I understand, on a car that has the steering knuckles forward of the front axle, the steer knuckles must point outwards in order to achieve 100% ackermann effect, assuming the steering rack and tie rods are parallel. (in a top view)
Also, I understand that when the tie rods are perpendicular to the steering knuckles, then 0% ackermann effect is achieved. In the case of the car with forward mounted steering knuckles this would occur forward of the tie rod mounting location on the steering knuckle, assuming the steering knuckles are still pointing away from the center line of the car.
So, in your case, moving the steering rack back towards the axle centerline should increase the ackermann effect.
note: when I say steering knuckle, i really mean the imaginary line from the steering axis to the mounting location of the tie rod ball joint.
I honestly don't see how changing the inner position of the CA front to rear would significantly affect ackermann.