what Marines would actually be useful for preventing illegal migration?

Trump has deployed 500 Marines to the Mexican border to clamp down on illegal immigration. Judging by reporting, this includes some pretty heavy units, with Ospreys and armored vehicles.

If the government were determined to do this well, and have an actual effect on migration across the border, what units of the Corps would it actually send? Some sort of surveillance assets? Intel units?

Not sure what the border patrol is actually short of.