I rode this route this spring. It will take you through Mexicali on, if not the shortest route, one of the shortest. Then south to the road along the west edge of Laguna Salada south to Guadalupe Canyon. Back out and onto Laguna Salada (this is the mildly tricky part), out to Hwy 3, and south to La Ventana. On the tricky part mentioned above, we rode around an ejido for a bit looking for the homestead of my riding buddy Henry's long lost family before we rode back out onto the dry lakebed. So disregard the ejido circles unless you want to tour it (NOT awesome).