Give her a "just off the boat," tribal kind of look, definitely. She shouldn't fit in very well, and of course she's not going to mind much, considering what she's been through. A devil-may-care heroine who looks like a shmuck but turns out to be unrealistically competent at something plot-critical could really work for this piece.
Okay, so how about this: thin, but not to the point of emaciation. She's wiry, obviously gristled and hardened by years in the broken wilderness, but inexplicably still kind of pretty. Maybe call that sort of beauty-despite-adversity "the single grace bestowed upon her by her aristocrat genes." Yeah, I like that. Use that somewhere. So, also, she's human--for this draft. If that doesn't work with the story, it's easy enough to change later on. Maybe even make that a subplot? She's got shoulder length, soft brown hair, and brown eyes. Scratch that. Make it pure black eyes. Pure black eyes are cool. Call it another gift from her mother, the duchess (maybe the result of centuries of inbreeding?) Give her a button nose with a lot of little freckles, too.
Put her in suede leather leggings, stained through with heaven knows what kinds of muck, mostly washed out now. The same kind of vest, over a course, graying cotton shirt. And moccasins. Yeah, moccasins are cool. No jewelry or fashion implants for now.
She's got to have that "yeah, what's it to ya?" kind of demeanor. Oh, and of course she has to be carrying around that Digital-Marble composition book all the time.