The correct way is to do a ground rod and neutral bond at the service drop panel at the main power board of the park. Check CFE regs about this. Any CFE office will even make copies for you, free.
That is exactly what the code I posted above says.
Because of a solid rock ridge I had to use a 2nd ground point in Flores de Las Penas. Then tie all seven sites to the 2nd point.
If you can run hot and neutral to the sites I do not understand why you could not also run ground from the main panel. Why would any second ground be necessary?
Even so, the 1st site had .4 - .7 volt difference between L1-LO versus L1 to earth ground. Site 2 was closer to one volt difference.
I have never heard or seen this unless something else is wrong in the wiring. Going back to the main panel neutral and ground are the same electrical point therefore should have the same voltage reading. If you do not get the same reading there is probably something wrong in the circuit.
You can connect a ground rod to the pedestal as long as you only connect it to the ground terminal in the pedestal. If the ground and neutral are connected in the pedestal you will have problems. Never connect ground and neutral together at the pedestal – bootstrap.
We use the term pedestal loosely here since we often do not see actual pedestals in Mexico. Even in the US many parks do not have what might be called a real pedestal. In Mexico the true RV pedestal can rarely be found as they are not something used in Mexico.