Just stay at one of the camp sites as it is only $10 and the campsites are quite nice. It depends which trails/ obstacles you take. All of the trails are marked with difficulty ratings. A lot of open open vehicles can do most of the park. In my open open YJ I could do radical ravine, heartbreaker, tnt rock garden, death valley, rebel blvd, sidewinder, twister, and twister's sister. It is definately an absolute blast both to ride and to watch others. I am sure Skip will set you up with a ranger to show you the park, and if I am there I would be more than happy to.
Yall may want to check out the Gulches forum at Gulches Off*Road Vehicle Park
or search for "gulches" on youtube.