Started to trim, fit and drill Left Aft skin (right on fixture). Trimmed centerline butt joint and aligned with cap strip pulled skin tight and drilled lower holes to anchor skin through bulkhead locations. I did not notice that the skin had shifted approximately .030 during the fit process, so my centerline seam will be biased toward the left side by that amount (don't tell the Oshkosh judges...LOL) Removed skin and drilled #40 holes on .75 inch spacing on centerline seam. If weather is still raining tomorrow (not flyable) , I will drill bulkhead holes, reinstall skin and backdrill.