Well first of all if she isn't a virgin, then she probably is okay with going against her parents, but you may have to be very careful how you work it.
If she is a virgin (I am guessing she is especially if she is as hot as you said as it sounds like she may be a little naive), ask yourself if you really want to take that from her if she is just a quick fling. If so, then make sure your intentions are clear. Then invite her to do something that can potentially take a full afternoon. Tell her as much. After you meet, and start getting into the mood, come up with a pretense for inviting her over. She will be much more likely to come because she won't be under the time restriction, and her friend won't be there.