I installed the single rivet that joins each rib to the spar. These rivets have to be installed now because the tank skin covers that region.
As Vans specifies, I installed fasteners in every other hole. I applied Krytox to the threads and used my electric drill to install the fasteners. Everything fit together very nicely.
Looking good! I still need to install the screws in the Z-brackets. 
I dimpled the holes along the flange on the rear spar. It was a little difficult getting the squeezer in this area because the flange is angled inward.
Vans tells you to remove a small amount of material to improve the fit between the spar and the skin. I just used a deburring bit to removed the material. I need to double check these surfaces next time.
