Could you get a babysitter to just stay late at the house, like 1am or 2am?
Basically you are afraid she is going to feel threatened by the Overnight option. You are right for worrying about this, because she probably will feel threatened.
One of the basic techniques for meeting women is the "false time constraint" - this means when talking to a woman you tell them you can only talk for a few minutes because "insert excuse here". This doesn't mean you leave the conversation in a few minutes, its just a way to make someone comfortable that you aren't going to talk all night. Without the time constraint a woman is going to try to not give you any false signals (not because she doesn't like you) but because its threatening - she doesn't know you and if you are going to get all clingy and follow them around wanting to talk all night.
You are setting up the opposite. Its almost better if at a point in the evening when you two are having the most fun you were called home. Leave her wanting more.
if the evening is going especially well, you can always keep the evening going at home. -- "we don't have a pool table, but i'll make you a drink at home and kick your ass at cards"
