Continue hiking on the dirt road and as it forks follow the dirt road east.
This is BLM land that borders private property.
On the dirt road at the saddle, look east and aim for the saddle, south of the Thimble Peak.
Make sure to leave the dirt road as this road enters private property.
A fence marks the Anza-Borrego Desert park boundary, you are allowed to cross it.
Now keep the fence on the right hand side, on the other side is private property.
As soon as the fence allows a 90 degree turn south, follow the fence more or less.
Eventually the track loops back along the foot of the Thimble Peak.
Warning:
The first part is BLM so shooting is allowed.