I'd be careful doing that JRM. I imagine that whatever they give you for a day pass - maybe a different colored bracelet - will not look the same as a guest's. Their whole thing is that they don't want you to bring in local, outside vendors. On the other hand, it sounds like they've gotten a little more lenient with things since we started planning our wedding there. Maybe they'll be okay with it.
Maybe do some research and see if the day pass is a normal guest bracelet (I can't imagine that it is or else you'd have people sneaking onto the resort and staying). If it is the same thing, then you would probably be able to get away with just the day pass.