This thread has me concerned. This is in Canada, but what inspections are required when building in USA?
Make sure you can put your eyes or an inspection mirror on every single shop head. The MDRA inspector may not look at every one, but you can probably guess that if they can't you'll be drilling out some rivets ;-)
As long as the inspector can see every rivet then they can see if they are acceptable. It takes very little time to rivet the outside perimeter especially with a pneumatic squeezer that if in doubt leave it undone until inspection.
I'd say hang it up "safely" and off to rudder building!
Looks like you're doing a nice job...