Rear quarter panel alignment

[QuadcityDMC]

I've taken off the right quarter panel before to line up to my door. I'm going to put new stryker pens and getting my doors set. Then aligning up the rear quarter panels as needed, is there a secret to getting them lined up pretty darn close. The panels as they sit right now need to come out about a half inch away from the body, should I cut into the fiberglass to allow more wiggle room for the panels to extend out or should I cut into the stainless screw holes to allow more outward movement?