I'd never heard of fluid film, had to look it up.  I'm not going to treat
the the inside of the panel.  The Rivieras have cabinetry on the passenger
side, making access much less than fun.  The rust around the seam is pretty
minor and confined to 3 small areas, so I'm not overly worried about it;
just want to take reasonable precautions against future rust.  I've got a
tube of SEM brand seam sealer from the autobody store.  So, my planned
sequence looks something like this:

Take areas of concern to bare metal, clean out body seam, feather paint
edges. (done)
Inject Rust Mort into seam and let dry. (should be 90 today, easily done)
Apply body filler to panels & block sand, being careful to not get filler
in the seam.
Apply glaze to panel & block sand, being careful to not get glazing into
the seam.
Apply seam sealer.
Prime.
Touch up with glaze & reprime if anything isn't quite right enough. (my
standards are a bit low...this is a campmobile, not a showroom car)
Paint.
Go camping!

I'm assuming that since primer will absorb water, I will want to apply the
seam sealer directly to the metal before the primer.  I will only apply a
clear coat if the rattle can paint's gloss isn't as shiny as the current
paint, which doesn't have a clear coat.

--
Brett in Portland, OR
"Albert" '82 VanaFox I4 Riviera