Small rust hole in trunk
 

I have a '87 300SDL that is generally rust free. However, there is a small hole on the lip of the trunk, below the lid, that needs to be fixed. Is there an easy way to repair this myself, or does it need to be ground out and have a patch welded in?

http://i.imgur.com/nRX46PO.jpg

If you want this to look good, you need to take out the glass so you can get below the window seal.

And when you've gone that far, the extra effort to weld in a patch panel instead of patching it with fibreglass or something isn't that much... So I'd reccomend that ;)