I f'ed up big time

[MGargano]

I got my new wheels installed today and, in the process of taking the old steelies out of the back seat when I got home to throw them into storage, one of them slipped from my grip and landed with a sickening CLANG! on the passenger's side sill plate (the panel under the bottom of the passenger's door). It put a nice dent in the metal panel and took a nice gouge out of the paint, exposing bare metal, all of which is still visible and exposed to the elements even with the passenger's door closed, which I know is not good.

I'm going to take it to a local body shop ASAP, but it won't be until Thursday (3 days away) and I'm wondering if anyone else has had similar incident in the same spot. I'm not sure if it can be replaced (since it's not a bolt-on panel) or repaired due to the location. The bare metal is exposed in about a 1/2" square and I'm wondering if I should cover it with something to prevent rust? Any help would be welcome.