OP, if you're still following, the only way you will know whether what you plan is allowed is to ask the security guard at the gate when you check in for your restaurant reservation. I would tell the guard what you intend to do and possibly how long you'll be parking there.
Outside of a few obvious rules (signs saying resort parking is not for theme park access), Disney does not expressly state a lot of rules about parking. This gives them the flexibility to allow parking at some times and either deny or limit it at others. The problem is you just don't know until you ask. As you can see, when you ask here some people will post their own experiences, which can differ quite a bit (some get 3 hour passes, others have never seen one). Others will simply make up their own parking rules based on what seems right to them and post them as if they are Disney's parking rules, which they are not. From what I've seen, the "parking rules" made up here tend to be much more restrictive than Disney's. My experience with parking at resorts is that the guards are much more likely to say yes than no, unless there is some good reason not to allow you to do what you intend. Obviously, if the resort is very busy and parking is severely limited, they will tell you so and probably suggest the best place to park your car.
Good luck and if you do follow the plan you asked about, please come back and post what happened.