I took my best stab at taping a centerline fore/aft down the top of the wheel pants. This was really tough. I finally got close by clamping the pants' aft fin vertically between two very straight blocks, then projecting a reference line down it with my laser leveler (sorry, no photos). I then drew a black reference line down that laser line. This differed from the blue tape line by almost 1/2 an inch, and looked more accurate by my eyeball check, so I used the black line.
