interior cleaning up / painting - need advice.

[eighteenninetytwo]

Some of the seam sealant is cracked and pulling away so I have a replacement tube, but when I pulled out the first bit of original seam sealant there is evidence of some corrosion underneath it, so the question is what order do I do things to kill it. There are two scenarios.
1. Rust is a bit down in a crack and can't be guaranteed to be covered by new seam sealer: my thought here is to spray in rust inhibitor (Napa stuff or POR-15 etc), then spray primer on top of that to completely seal, THEN new seam sealer, then primer and then cover with the spray in bed liner.
2. Rust is easily get-at-able with seam sealer: Cover with Rust inhibitor, then seam sealer then prime then bed liner.

The only difference really is extra primer to ensure rusty area is sealed against external moisture but my worry was that seam sealer would then be bonding to the primer as opposed to the actual metal. Does this make a difference? is there any reason I shouldn't follow this process with the whole interior?

[68Timber]

I think you'd be fine with POR then seam sealer.