These pollen testing are interesting. Pennsylvania is pretty close to Ohio; Philadelphia, maybe? That could fit in with the soot from industrial activity and it is close to OH.
Wonder if she was carrying a purse, backpack, etc. that had stuff like tweezers, toothbrush, hairbrush, maybe a bit of money. Her eyebrows just look so neat and tidy, and I can't see any little new hairs starting to grow in. If she was travelling, she would absolutely have to carry those tweezers with her to maintain her brows. Brow hairs grow in super quickly.
I'm confused on why she wasn't sexually assaulted if she was the victim of a truck stop killer, because that is very, very common. She was very pretty, and it would makes sense if she caught the eye of a sicko. If she turned down a violent truck stop killer when asked for sex, it seems more usual that he'd just rape her anyway. Maybe he bought her some dinner; they went back to the vehicle, and he asked to have sex with her. Something like "You owe me for the chicken and fries." She said no, and he got angry and hit her on the head. It was suggested on FB that the marks on her head could be from a tire iron, which could fit in with the scenario. He finished off the job by strangling her. I still feel like he'd rape her anyway, but just a thought. If she had taken her shoes off, and left her bag in the truck, then I could see why he wouldn't bother to fish them out and dump them with her body.
The part about the West pollen adds confusion. It makes it sound like it's from the Southwest. I really wonder if the jacket was her killer's, and he was a truck stop killer who wore the jacket while travelling. Or maybe she was returning from a vacation from the Southwest, and was hitching rides from the West to the Midwest and almost made it home. The jacket looks a bit big for her anyway, though it might have been to fit her chest, or to accompany clothes underneath. If the other clothing items were looser, I'd reckon it was just her style, but they are pretty form-fitting.
I just can't get over my gut feeling of her not being a hitchhiker, but maybe she was hitchhiking for the last few days of her life only.