DO NOT use the Polynesian beach if you are not staying there! Last year, a lot of people did the same thing you are suggesting and TRASHED the beach! People who paid for lagoon views and had patios had their chairs stolen from people who weren't staying at the Polynesian. People who decided to "use" the Polynesian took all the pool towels, all the lawn chairs and basically ruined the view for all the people who paid to stay at the Polynesian on July 4th. In my opinion, unless you are staying there on the 4th of July, you shouldn't be taking up the viewing space of the people who are paying a lot of money.
(edit) I am not assuming that you will personally trash the place, but when rumors like this spread, selfish, uncaring people can take advantage. Yeah, they are supposed to check IDs but I also read here that even though people were asked to leave, it wasn't enforced.
If you want to be far away, go to the TTC down by the boat launch or some other public area.
If you are dining, you will receive a parking pass for 3 hours...and while I was there in December, that 3 huors was being enforced. During our week there, I personally saw 3 cars being towed away.