OP, I was like that when I was a child. I could not even sleep at a friend's house who lived right across the street from us. Everything from the lighting in the room, the smell, etc. was too overwhelming for me and I got very anxious.
It will take time and patience. What helped me was to take as many familiar items with me as would fit into my suitcase.

Two of my kids have HFA and one of them take meds for anxiety (Not a surprise given my own experiences, right?), and we literally have to take their blankets, favorite cd, etc. with us to get them to sleep elsewhere.
I think she might have gotten to a point where just the anticipation alone is freaking her out enough to send her into a panic attack. Teaching her techniques to help her feel confident might help. Finding something to do when she cannot sleep will likely be key to her success. If she can fall asleep somewhere else "naturally" it will help her feel like there is less pressure on her.