I would suggest that, at this time, the southern border states of these, once great, United States of America, secede from this failed experiment and create their own federation. Once that is achieved,they then can institute absolute border patrols and enforcement.
This would be beneficial to not only their own, newly founded country, but to the existing, although quickly dissolving U.S. I am sure that their new government would be more amenable to protecting the rights and privileges of their citizens. It is very likely, that they would even adopt the existing U.S. Constitution, as their "law of the land".
Perhaps they may clarify a couple of items, such as. No Modifications to the original 10 Rights in the Bill of Rights. Clarify that freedom of speech is absolute. Clarify that the right to bear arms is absolute. Clarify that the nationality of a baby born in this country is identical to that of it's parents. Clarify that though the several states have full control of voting in their states, minimal requirements of absolute ID must be adhered.
They may want to enter into the first articles, that all positions of government have terms limits. That their Supreme court does not have the final say. If a super majority of the states representatives vote against a judgment, then that judgment is null and void. They may add that the Presidential bureaucracy cannot issue any regulations that are not first voted upon by the new house and senate, and that the size and scope of any bureaucratic entity shall be enabled ONLY by a consensus vote of The People's representatives.
But in the end, the primary cause and argument for the dissolution of their membership in this country is that they require the right to protect themselves from the invasion of foreign enemies and armies.