As an addendum to Rick's procedures, which a lot of builders have used with success, I would add the following: when I did my ribs, the entire assembly was clecoed together and I would remove one rib, proseal it back in place, and then rivet it. I preferred that because it insured I set the rivets 'wet' and riveting also drove a little more proseal out between the skin and ribs. I'd mix enough proseal to do a couple of ribs and encapsulated the shop heads before proceeding to the next pair. Doing it in small amounts keeps you from rushing, which inevitably leads to mistakes and proseal getting everywhere.
Encapsulate the rivet manufactured heads on the rear baffle. Yes, they're sealed but I wouldn't trust to that. Also, it's pretty common for the proseal between the skins and rear baffle to spread the skins slightly, causing a slight misfit when the tanks are attached to the spar. The RVator had an article where a builder came up with a bending tool to adjust the skin behind the baffle. What I did instead was lay some saran wrap over the spar and clecoed the tank to the spar until the proseal set. As a caveat, another builder tried this and reported that the proseal stuck to the saran wrap and I have no idea why we had different results. However, you could substitute some of the thin plastic used in fiberglassing; I'm reasonably sure proseal won't stick to it. Anyway, after the proseal set, I did the final rivet lines and my skins were snug to the spar.
