I read what you wrote several times, but I don't understand.
If you have a dinner reservation at the Poly (or any other Disney hotel) you can park in the hotel's parking lot. The guard at the gate entrance to the Poly will ask if you have a reservation. If you have one, they'll let you in. I know, I've done this many times. They let in hotel guests and guests with restaurant reservations.
So what am I missing? (and it wouldn't be the first time I missed the obvious)