I was in a similar situation of needing to leave and return. When i did the AP preview, you were given a wristband. I was told when I left that I didn't need (or could get a handstamp), I was to leave the wristband on and show the AP. Curiously, they never did ask for the AP Preview Printout, but I would keep it in case.
Anyway, just wanted to warn you that you may potentially need to leave a wristband on all day in order to return.