Well, since there was only one entry for September, this month is open to all Mustang owners that have not won so far this year. I'm sure you've read the rules by now, but here's a polite reminder.
Now, the theme for the month of October will be Halloween based. And because of the early start, it's going to be a touch different then you were thinking. Because I'm sure there are a ton of houses with pumpkins already carved out.
Dress up your car as a Jack-o-Mustang. Plasti-dip, paper cut out and taped on, masking tape- doesn't matter. Just have a Jack-o-lantern style face somewhere on your car. On the door, hood, windshield, wherever. But get a few good angles of it. At least two pics. Be creative. Scary, funny, goofy, however you would do a pumpkin. Just do your car.
But don't think because you have 4 weeks to do this, you'll be in. First ten entries by October 15th. Then a showoff, then the votes.
Hopefully since you don't need helping photographing, this should be a month you can finally just do it.