Sorry, I haven't been keeping up here with my usual thoroughness lately (busy as hell with other things), so I haven't been following your threads on the new project.
For anyone interested in this topic, I highly recommend Patti Bellantoni's book,
If It's Purple, Someone's Gonna Die (The Power of Color in Visual Storytelling). As the title suggests, purple can be a visual omen of death and transformation. According to the author, it also holds "a powerful sway in the realm of the noncorporeal, the mystical, and even the paranormal."
With a lighter-skinned actor you might need to use it in small doses to keep her from looking washed out, but violets and purples are often flattering to darker complexions.
However since she's supposed to be 'young and innocent,' you might also consider using purples elsewhere in the shots and instead costuming her in purple's complement, orange. Identified in the book as the "sweet and sour color," oranges can suggest openness and naïveté. A pale orange or soft coral would also make the sweat and dirt "read" well on camera as the scene progresses.
Either would "pop" against the browns and greens of a wooded setting.