I am going to be driving by in the evening after they are closed. Is it possible to pull in get a quick picture then leave? Or is there a gate preventing access?

I was just there at a time no one else was on site. There was a low gate over the bridge (and it wasn't shut), but that's only a few steps from the field. Pictures could be taken.

Pictures can be easily taken. I would suggest going back when they are open to experience it. It's breath taking!

To my recollection, there is not a gate. This well kept family friendly site is fairly open and easily accessible, but there are hours of operation. There's no charge to take photographs during operating hours.