ABDSP is a HUGE park. There are many places to camp, both developed and remote. However, you will be limited by the size of your TT.
The official park magazine, available free online, has maps, campground descriptions, hike descriptions, and contact numbers for further info. Take special note of the restrictions on dogs, ground fires, and wheeled vehicles.
2016 Anza Borrego Desert State Park magazineSome primitive camping areas long popular on blogs and such, have had recent ownership and camping policy changes. Examples: Clark Dry Lake, Rockhouse, and Culp Valley. Call the Visitor Center for current policy and conditions.
2006 Tiger CX 4x4, 8.1 L gas V-8, Allison 6-speed