I've had a character named Wild Elf for quite a while, who fits this description exactly. She's a hunter/archer wood elf, who brews her own poisons. She never enters cities or villages, and the only buildings she enters (other than ruins) are a couple of isolated inns.
The biggest problem with this kind of character is trading. There are only a handful of non-city merchants, and no general-merchandise merchants at all. You can't do many quests, because most of them involve entering a town at some point.
On the other hand, you can find just about anything you need to role-play a hermit. There's no shortage of weapons, arrows, armor, potions, etc., as long as you're willing to fight for what you need.
Some of the camps even have safe long-term storage. (An open-top "grain sack" is safe to keep your stuff in, since they don't respawn.)