One thing you are overlooking is some bikes rust from the inside out
and nothing you have mentioned will do anything about that. Worrying
about rust to the point of failure means something needs to be done
inside as well. Many forks have vent holes that some fluid could be
introduced thru. Besides water.
the fork could be sand or bead blasted to remove all old paint and rust
on the outside and a new paint or powercoat applied. but that won't do
anything for the likely rust on the inside.
Maybe one of those rust stablizers poured inside. Or fill the fork
with a heavy oil. Something to slow the air & water rust process.
I remember riding alongside by brother up a hill one time when a fork
blade came apart about 1/2 way up the blade. No warning. No visable
rust. No snap. just separated. Rusted thru from the inside. I've
seen other bikes with rust thru holes too.
After looking at the face plant injury photos at the walmart lawsuit
site, i'd even consider just buying a new fork, filling it with a frame
prep, spray with the army color paint.
Rick