What type of thieves? Animal or people? For animals, here are some possible solutions.
Motion detectors with alarms, will scare both critters and humans :-D
Problem is it is across from my unit and is behind my disable neighbor's unit. Is there a type of fencing or something that is possible?
For the humans best guard is a dog unless you want to lose some sleep. Or maybe some of those battery operated, motion sensor lights. Wonder if you could hook up a recording of someone shouting "Get out of here"?