You most likely wouldn't be able to park at the Poly. They're pretty strict about making sure only people staying there or that have reservations are allowed to park. If you park at the TTC and walk over, you'd probably be fine. We stayed there this past July 4th and they did a horrible job of managing the non-resort guests. The place was completely overrun and it was impossible to get onto a monorail or boat after the fireworks were over.