Two people working together really helps.
Hold the panels in place and mark enough screw holes to hold the segment protectors in place. Mount the protectors and hold offs in place with a minimum number of screws, (easier to make adjustment if necessary). drill, install, and seal the remainder of the screws.
I used SS screws for all fasteners instead of rivets. I sealed and secured screws with aluminum sealant.
Be sure to use the "newer" standoff assemblies - they are much superior to the older, and much smaller, holdoffs.
My install can be found here: