Don't know of any "4x4 dedicated trails" but there are thousands of miles of back bayou dirt/mud roads down there. Ain't no mountains or rocks down there so greasy mud is your biggest obstacle Get some decent tires and go practice. Once you get a clue contact some of the local 4x4 clubs for tougher stuff. Most of the club stuff down there is built for mud bogging. If you want rocks you'll have to venture north of NOLA. For practice I'd maybe head south toward Venice and take off on any bayou road you fancy. If you're lucky you'll get one of those daily hour long rain squalls that greases things up nicely.