Heard from a local builder buddy (he built a Sonex from scratch) about a technique he used to locate holes to drill when you couldn't easily get behind the fastener you were trying to drill the hole for.

Fix a laser to point at the fastener with the wheel pant cover off, then put the cover on and mark the spot where the laser is pointing.  Here's his blog page on what he did.

So, I ordered this today.  Cheap and I can do two at a time! ;-)  Probably just do the top two then measure down from there to get the other two.