Mixed up a batch of proseal after scotchbriting and cleaning the mating parts. I ran a bead of proseal on both rivet lines and then on the flanges of both ribs and covered the complete flange.
Once in place, the ribs were 100% clecoed and I also used a couple of clamps to hold the skin tightly in place.
Once clecoed, I flayed the joints so that there were no gaps.
I'll give it a couple of days to cure then wet set the rivets.
The vent line was also connected, torqued, and a little proseal added to keep it in place.