I would make it $200/day/alien, make it strict liability (plausible looking fake ID no defense), and make ANY police agency be able to enforce it, with the arresting agency keeping the money.
Instantly, catching illegals at work would be a higher priority than manning speed traps. Any business caught with illegals once, would get daily visits looking for illegals for the rest of the month. Businesses that made good-faith efforts to not hire illegals would not be hit hard by the occasional illegal that makes it though the screening process.
Also, make it explicitly NOT discriminatory to require fluent English from all applicants. And Ebonics doesn't count as English.
Force everyone into the i9 system. Prosecute people for SSN fraud.
But if Ivan comes to work with a green card, how will we know if his family is here illegally if they don’t work?