Two… using one crappy owner’s manual.
How long does it take?
Apparently, it takes about 45 minutes due to crappy owner’s manual. The picture showed the screwdriver under the flange for the tail light assembly where it says "Remove push-pins" In actuality, if you want to succeed at removing the push pins without destroying anything else… you need to use TWO screwdrivers, one in each of the little slots that separate the bottom of the push pin from the top of the push pin, and pry the top of the push pin off. After about 30 minutes, we finally figured this out. At that point, it took about 15 minutes to drive to the store, get the right light and replace everything.
And just for the record… we didn’t destroy anything in the 30 minutes it took us to figure out what the CRAPPY OWNER’S MANUAL couldn’t seem to diagram.