You're right that contacting too soon is needy, but don't mention that you're going out of town when you set up the date. To you, she should be just another HB that you can spend time with and if it doesn't work out with her, you can pick up someone else. That should be at least the vibe she is picking up from, but in a very playful way.
However, mention that you're going out of town while on the date, and don't make it a huge thing, like, "I really like you and I need to seal the deal NOW!" That will scare her off. In the middle of a conversation, let's say your talking about each other's future, casually throw it in like, "since you're so cute, I'll have to update you with how blah is going while I'm away for the next two weeks."
Just make sure that you two enjoy your time together and after you have mentioned you are leaving and you get into a normal conversation, tease her about the things you will do with her when you get back. This will create anticipation.
I tried to create a specific example, but I'm drawing a blank at the moment. Good luck
