Just tell the guard you are coming to the resort to eat. Since the resort is not close to a theme park, you should have no problem parking there. DH and I stay at the Boardwalk. But, we like to drive over to CSR at night and walk around the lake, and perhaps have a margarita at the bar. It's so pretty at CSR. We've never had any problem entering the resort or parking there.
We never have an ADR when we visit CSR. They'll probably ask for a form of I.D., like a drivers' license. No big deal, although for the life of me, I can't comprehend what that accomplishes as far as security since it's easy for terrorists to get drivers' licenses. I suspect WDW thinks asking for I.D. gives them some kind of legal defense in the event there is a terrorist attack. The old -- it wasn't our fault -- we I.D.'d everyone. Oh well.
Enjoy!