The one with the secure parking is also called La Pilarica It is on the east side of the highway. Southbound, just over the bridge at the southern edge of Los Mochis exit right and go back and under the bridge.
Northbound, keep an eye out for the bridge coming up and exit right. There are signs as you approach for a rest area, which is in fact the Pemex.
We have stayed there in the past but now we just leave early. stop there for fuel or lunch then carry on. San Carlos-Mazatlan. Leave at dawn, arrive at dusk.