In the past, I have also used internet based security cameras and alarm system connected (along with signage) to a wifi hotspot (jetpack etc.) to do this after changing locks and better securing doors and windows.

@Preeti Tibrewala install an internet connected camera to monitor who is not cleaning up after themselves.

Howdy @Nick FerroniYou should have the septic system inspected (camera). 

There are a lot of inexpensive products on the market now.An alternative to this would be to install a fake camera.

Just a few hundred dollars would do.Buy business cards, bandit signs, enough for a small direct mail campaign, some nice looking clothes to make you look trustworthy if you don't have them.Cheap digital camera off of ebay/craigslist.

If your friend is looking for a self storage unit that's reliable and secure, besides the obvious things like security cameras, I would advise him to look for two things in a facility:a.

I also can not find a company that can do an inspection via camera.

As for the homeless population, install bright lighting and cameras if possible.

The pool contractor could use a camera to view below the cover for example.

I'm not sure the price for that.  4x the sewer camera scoping if you are going to do that @ $100-200 a piece.