I'm afraid what we're going to have to do is help the ranchers wall off their own property. Not that it's going to be easy.
How many uneducated, non-english speaking migrants are getting valid green cards anyway? Seems to me it should be simple. If one of these underfed little mestizos hands you a green card or a SS card, it's fake.
Unfortunately the nature of a ranching operation precludes a walled compund for safety. Besides such "protection" would be illusory since they might serve to keep victims inside if a determined force were to penetrate the perimeter to mete out some border retaliation...
A far more workable solution is to recruit the ranchers as "in place" recon units. Give them military radios and night vision gear and the training to use that equipment. With the national guard on standby, a rancher sighting a large group of illegals with maybe a covering force made up of MS 13 or the Mexican Army...could simply radio in the sighting without anybody being the wiser. Then a swift reaction force of Apaches and Bradley's could respond.
The US Border Patrol is forced to withdraw in the face of Humvees mounting M2HB 50's because they're outgunned and of course subject to STUPID Rules of Engagement imposed by the feds. I wonder how the shoe would feel on that other foot across the border when a flight of Apaches screams in to politely inquire if they need directions back to Mexico City?
I wouldn't rely on a paper document at all.
Every employer should have access to a government database that can validate the information provided in seconds.
Input SS#, previous employer, addresses of previous employers, home addresses for previous five years, place of birth, mother's maiden name. Everybody legally here has an electronic trail a mile long. If somebody gives you an SS# that is already in the system as employed 50 miles away, retired, dead, different home address, etc. you should find that and know not to hire them. If somebody pops up as already employed locally, ask what their hours at the other job are and check with that other employer.