I know they’re prone to rust; I own two but I’ve never seen rust in this location before. Would this more a much more complicated job than let’s say, repairing the wing?

 

The real problem is not the rust you can see, but the rust you can't see. Surface rust can usually be
addressed and nullified to a large extent by various treatments. Rust coming up through the paint
is a different animal completely. One that is never totally subdued unless the affected parts are removed
and replaced. I am certain there are those who will swear they treated said parts in place and the
rust never returned, however that has not been my experience.

 

Rotten, but what I don't understand is how far along the inner it's travelled, but if I drive at 60mph into a salt bath and those sill end panels aren't sealed.....