How about a 100 foot wide moat fed by water from the Rio Grande river, and populated with gators & crocs & unwanted pythons from Florida? Throw in a few bunches of Piranha fish to feed the crocs and that would drastically reduce need for border guards.
A real 'shovel ready' job.
California would want the water, Gator tacos would become a staple diet on the south side, and you'd be able to spot the illegals by their alligator shoes.