You will be taking the exit for Mariposa/ Truck route. As you stated stay to the right with the trucks as you cannot get a MH through the other lanes. When you get to the border you keep going onto a wide freeway. Toll Road. Watch for signs that say cars/ Rv's. Right at The first border check station get into the right lane. Go slow. A border agent will come out and ask a few questions. Sometimes they go inside your unit. Your next stop is where you get the permits. There are signs. Large parking lot. Have fun!
Moisheh