In NJ? You probably want to get there the night before if being in the first row is imperative for you. Otherwise, I think you'll get in no problemo by getting there 6 AM.
Saw Mark's comment re: Miami Elevation - he's right, we did sleep under the stars but that was in Miami on a clear night and I think we did it on purpose as we knew a hotel that night would be useless. Well that was my thought anyways lol. And it was the final Elevation show, so we were hardly alone, I think we were 53-55 or so at like 10 PM the night before the show.
Toronto in September is nice. I still go camping up north that time also so sleeping out or with some temp shelter is doable. Layers are your friend as it will get really warm the next day and you'll want to peel some of for sure