Ah, I think I understand. You're concerned that if you use the "Accept Axis" button, during the calibration wizard, you won't get the full range of motion in the sim. That should *not* be the case---using the "Accept Axis" button should force X-Plane to treat whatever range you can *actually* move the controls through as "gospel" for the entire range.
So, if you move the controls as far as you can, and that winds up being 20% of the hardware's range in each direction, and you hit "Accept Axis," when you're actually in the sim, you should find that moving the controls as far as you can causes the plane to go to full deflection as well.