You're not gonna find anything too crazy there, but there are definitely miles and miles of largely unmaintained dirt roads. You can cross reference the map on their website with google maps satellite to get an idea.
Anything not shown on their map is either gated or marked. You'll see little offshoots off the main trail that someone has gone down before, but they're clearly marked with an orange sign. Some of the little roads aren't labeled one way or another, and just lead to an oil pump or something. Not sure if they're legal or not, I checked out a couple of them, but thats your call lol.
Lots of stuff to explore thats clearly marked though. Pretty fun, especially with a good rain lol.