The most important item that you need in Mexico is a voltage regulator to protect against over voltage and under voltage, specially for the refrigerators and microwaves and any appliance that has a motor or circuit board as in computers, TV's, etc.
navegator
My rig comes with one. But just shuts down power source for protection. You need a voltage corrector on top of that.
The ISB has lowered the voltage for us. The park we stay at there are times when the voltage is at 137 my rig would cut the power off if not for the corrector.