What could go wrong?

I have a rental where I am very slowly getting renovations done. It is empty, and looks like crap.

I met a recent immigrant who is looking for a place to stay. I would only have them pay utilities. It would be a slight advantage to have someone there for security. Probably for a couple of months.

How can I protect myself from squatting/needing to evict? I'm not too worried about damage. The place needs gutting anyway. What problems am I not thinking of?