I was in a relationship like that (minus the hot tub!) for about 7 years.
For what it's worth, here's my opinion.
As you are moving away - I'd tell her how you feel.
If that "weird's her out" you COULD always set about regaining her trust by not going weird on her yourself.
If it turns out that she has feelings for you you could take it from there.
My experience tho of this sort of a (possibly) onesided relationship is not good.
It eats you up because you want more and it's unrecipricated but you live in hope.
I also believe that if it turns out that she definitely doesn't want the friendship to go further YOU should put some boundaries in place.
The hot tub stuff is off limits and if she repeats it again I feel she is not being fair because she's sending out mixed messages.
I HOPE that she wants to develop the relationship.
My gut feeling is that she doesn't.
When I look back over my previous relationships I sometimes think about the times I seemed to meet the "right" person at the wrong time, and I wonder what might have been.
But when I think about the person I knew, who sounds alot like this girl, I really don't view it in the same light.
Neither of us were attached, the timing could have been worked out, and the opportunity was there. I told her how I felt.
She didn't want to take it any further than the "shopping" and "dinners" that you're having.
We did continue the friendship but in the end I needed someone who wanted more with me
In the end she didn't WANT it.
Not much you can do about that.