It all comes down to enforcement. If those hiring illegals had to pay a sufficient penalty, the illegals would be unemployed, and they would self-deport. If the Free State of Texas had sensible laws for legal immigration that allowed guest workers to enter legally as needed, there would be even less demand for illegals. Like most who support secession, I don't object to legal immigrants, or to legal guest workers, just to criminals.
In the 70’s several ranchers wives brought the wives of their Mexican hired help to our shop. We visited while they shopped - except when she had to go read the cards to them - and according to her, they had to go to the border to pick up their workers, with proper documentation, and after the period they were hired for, return the families to the border for return to Mexico. They were also responsible for the workers and their families, while they were in the United States.
Worked pretty darned good!
Okay, but I suspect you'll have the same problems with enforcement that we have today.
If Laredo is 95 percent Hispanic, McAllen, 89 percent, and Brownsville, 86 percent, it's going to be hard for non-Hispanic police or enforcement officers to cope with illegals, and Latino police or enforcement officers (or those of any ethnicity) are going to be faced with a lot of pressure to allow what's been going on to continue.
Also, the idea that Texas is somehow all of one piece may not fly. Texas may be faced with internal secession movements itself.