An odd one this..

The frame that my glovebox bolts to is getting very crusty due to past water ingress

is it possible to replace that section?

It's still solid enough to paint " I think"

but eventually it'll rot through..

my car has weird issues! lol

Paint a rust inhibitor on it then paint it it'll be easier that trying to repair it in car

• on the rust inhibitor. My Series 2A bulkhead was rusting when I got it so I thought I’d hit it with some Tremclad and deal with it properly later. Another 25 years later it hasn’t really gotten any worse.

That dot was supposed to be a “plus” on Symes comment.

That metal ain't treated at all (like in most cars' interior unpainted metal), so with a proper treatment and - especially - fixing the water ingress you might not have any more issues later on...