It's a good idea to have your ADR confirmation # handy. As a local, I often go to the resorts for meals, and if it happens to be busy for any reason, they will cross check your ADR confirmation against a list before letting you in. I would say that's happened to me at least a dozen times over the years.
Once, a few years ago, I had an ADR at the Concourse Steakhouse at CR, and I was turned away at the guard station and told to park at the TTC because of a huge in house convention. In all of my years of going on property just to dine, that has only happened to me one time.
The self parking for GF is across the road from the resort. The last time I was there, there was no gate access there - it was just open parking. Have they put up any barriers that would have required the previous poster to use valet instead of self parking? It's a long walk from the self parking, but I've done it (in cooler weather) without a problem.