Plant cameras, then subsidize them a little:
Collect good imaging from EVERYONE who comes —let it go on for YEARS.
Then at a single appointed time go and BUST THEM ALL.
Japan used a fake “Persian New Year” celebration with lots of marketing and “free” stuff to get rid of their Iranian Illegal Alien problem all in one, huge swoop.
They’re all gone, now.
Yes, a little bait and a hook.