About the same as I think of any blanket amnesty for any group of breakers of the common law. One of the reasons people gather together into a nation is security from invaders. One of the prime mandates for government is to protect the people and destructive influences on their society from invaders.
Not only is this in the ancient common law, but it predates it. To give amnesty to such people that invade our country without our permission and without our leave is to break the foundational spirit of our system of law and encourage more invasion.
Our only real option is a long process of identifying them, apprehending them and summarily escorting out of this country in the cheapest way possible. Discourage the reason they come here by making their employment a criminal offence and agressively track down and prosecute any individual or business that uses them.
I would also station a rollover detachment of National Guard, with regular military advisors, for the states that border Mexico on that border. I would make weekend warrior duty consistent with that task, with orders to apprehend if possible and, if necesary to stop them from entering, shoot to wound, if possible, to kill if necessary.
I would post the details of those orders in Spanish at regular intervals along the borders of those states, with the caveat that, if wounded, medical attention will not be had in the United States but in the country of origin. If the wound will prove fatal before medical attention is reached, that would be just too bad. 