Sirjet take a look at the east end of the Hwy 515 W bridge. There's access from the north side of the highway at that location. You'll be right at the bridge and pretty close to the main creek channel.
You can access Little Mustang creek on Hwy. 17 right next to the bridge on the west side.
+1, been launching there for years. Be sure to pay the launching fee of $5, put it in the box on the road to the ramp. In his shop Joe sells many types of lures and soft plastics, many of which he makes himself.