Shoot, I go a good inch back on the outside, the whole tank bay, around landing gear mounts and a good bit of the wing bay if not all of it. Anywhere oil will seep in gett a once over. I thin mine down pretty good to make the coat pretty light, as I get near the end of the mix and most of the alcohol has flashed off I go back over the main spots I want protected.
The planes seem to last longer when I do all of this.[8D]