I started this session by clecoing on the vertical stablizer's skin, but I started to realize that it would be impossible to access all of the interior rivets with the rear spar already attached. That's when I figured out that I shouldn't have riveted the rear spar on yet, so I drilled out the 5 rivets holding it on and started the skin assembly as intended.
I found it easiest to re-use the wooden wing cradles to support the vertical stabilizer upright, even though they were intended for much a wider part. Then I could stand on a step stool to reach down inside of the vertical stabilizer as I bucked each of the interior flush rivets. I was able to use my hand squeezer for the flush rivets along the exterior seams, though it helped to have a narrow-nose squeezer yoke in some places.
Once the skin was fully riveted to the ribs, I could then cleco on the rear spar and rivet that in place too. This was just a matter of reinstalling the 5 rivets that I previously removed (3 of which were blind rivets), and then installing the two rows of flush rivets along the rear spar flange. I was able to install almost all of the flush rivets on those flanges with the hand squeezer, however the few that were very close to the white brackets had reduced clearance around them so I had to buck them with the air rivet gun. These bucked rivets came out less than perfect due to the narrow space available, even when using the angled foot bucketing bar, but I didn't feel that I could improve them further after making a few attempts.
What's next? Time to start on the rudder.