House flipping the "homeless hangout" -- advice needed

[William Barr]

Recently we've started work on an inner-city house flip. Turns out, this property is a known homeless hangout. We didn't know this at the time of inspection, but since then we have had several run-ins with 2-3 homeless people camped out on our property.

The first time, we called the local PD and they sent the homeless people away - no arrests or anything like that. However, they are coming back and stealing things/trashing the grounds. The catch is that this is happening at night, so we can't just drive by and monitor it during the day (they are out walking the city during the day). The other catch is that this renovation needs a full rewire, so there's currently no electrical for a security system to be installed.

What is a good solution for us to keep them from trespassing and damaging the property any further? Open to all ideas. Anybody have firsthand experience dealing with this situation?

Thanks!