Image 1 shows how I use the Sharpie mark to help line up the Strut - not to worry, it will be as perfectly aligned as I can make it before I drill - my edge distance is counting on it! In Image 2 you can see that I'm Match Drilling the Strut to the Rib so the Sharpie mark must be correctly aligned now. Image 3 shows me Match Drilling the Strut to the Outboard Bracket.
Strut Clamped to Rib - Note Sharpie Mark in Tooling Hole