Been following along but first time commenting on this thread. Much of what has been said about Savannah's personality reminds me of myself at that age, so I wanted to share a few things that haven't been considered. I'm a farm girl through and through and I've raised 3 raccoons and later turned them loose once they reached breeding age. I can't even count how many birds, field mice, pigs, goats etc. I brought in the house and nursed back to health. I loved the outdoors no matter the weather. The barn was one of my favorite places, I spent more time in the barn than in the house no matter how cold it was. The barn was actually where I met my close childhood friend. Our parents didn't know about it for weeks. Fortunately for me, my friend, a boy, was a good boy. So I could see how Savannah could've made friends with someone without anyone knowing and no electronic trail.
I also had a tendency to bring home human, "injured" strays as well. Is it possible she met someone, male or female who took advantage of her nature? Maybe the sheets and clothes were for a friend who needed to run away for safety, then once she snuck outside, she was abducted? I know this sounds pretty far fetched but nothing is adding up from what we've learned so far IMO.