Is this heavily trafficked, and do they allow wilderness camping? I.e. camping outside of designated campsites?

There is a campsite near the parking lot on the Alabama side, and there are a few campsites on the way to the falls. The only Porta-potty is in the parking lot.

I've been there a couple of times and there wasn't many people. I always go on weekdays though.

My last trip there wasn't alot of traffic and yes there's campsites everywhere.

This Trail gets a lot of traffic, and there are lots of campsites available.

There is definitely some traffic on the trail and we saw several campers last visit.