Sounds like you just "lucked out" with some rotten kids nearby.I've had some success with "security cameras in use" signs, you can buy them at the Home Depot for $3. 

What is the best cameras to use when taking video / pictures of your property for sale or rent?

If leaks are found, G&M can then scope the system with a camera to determine the location in order to make repairs.

monitor the gas, water, electric and door locks, maybe even cameras too, (cameras is what i do for a living).My utilities are not separate, so I'd like to monitor them individually, so i might as well make the meters smart.  

Doesn't hurt to get a sewer camera down those pipes and take a good look on a potential investment.That way you know for sure whether you need the "whoosie whatsit " or not.

We did get a new-in-box big screen TV (50", but about 15 years old), a new water heater, some tools, a couple 8mm video cameras from the 1960s and other random stuff.  

Joel,What type of camera are you using?

Maybe adding cameras but not sure if this provides much help with these kind of activities.

He has tried to install cameras on his own in the front of house recently without my permission.

Odds are good the listing agent will just collect the buyers and sellers commission in that situation, so all you have done is given up representation and not saved money.As far as the comment about recording cameras, it is very common for sellers to place hidden cameras in their properties.