I put PeelNSeal all through my '90 Westy about six years ago.  Doors,
slider, rear hatch, engine lid, under rear seat, closet floor and a few
other places I can't even remember.  Any place that when tapped on sounded
hollow like it would echo or resonate.  Not one smell, not one hint of rust,
nothing sagging or falling off.  And I've slept an average of about two
months plus a year in that rig ever since and still alive.  So I have little
concern.  And BTW, it did a very good job of cutting down on noise.  A
couple of times I've had people, hearing the sound when I close a door, ask
what I'd used on the inside.