OK, I talked to the tank sealer guys at Caswell and they said I ought to scuff up the insides of the tank since I can and it'd help adherence. They said go ahead and glue everything up before dumping their sealer into the tank to coat the interior. So that's what I'll do.
It's been a long process so I'll take a sec to make sure everything's wiped down clean with acetone after sanding and vacuuming all the dust. Nothing but rubber gloves at this point; you don't want any of your finger grime/oil getting onto joint surfaces.