As noted A-B State Park is one of the few parks where you can camp at
large.  If you prefer a restroom there are some areas for open (free)
camping that have nice pit toilets.  A couple that come to mind are
Blair Valley and Mountain Palm Springs, both are just off the S2
southeast of the Scissors Crossing.

Some areas (such as Yaqui Well) can be soft sand some times of the
year and have you wondering if you will be able to get out again but
the 2 mentioned above are solid ground.

It's a big place (largest State Park in the US IIRC) so enjoy some solitude.

Geo