How about this: no masks, no weapons (if they feel they are in danger they can call the cops who already have more weapons than they possibly need). Every time a citizen is detained in jail, detaining agent and their manager lose their paycheck for that period. Family with kids jailed and separated? No paycheck. You know, do it in the Christian compassionate way, not in the shooting single moms way.

We would have to pass a more general law that said children cannot be separated from their parents based on any crime the parents have committed, as there's no reason to special-case illegal immigration.