This is so common now that it should not surprise anybody.That all being said, vacant houses need either security systems or daily monitoring.

This is a general response, naming attributes, based on your post and what I would want personally:-Monitored, police response -motion sensors in appropriate areas-cameras both indoor (public areas)  & outdoors - motion activated, records to cloud, holds for minimum 48 hours, w/ audio capability-remote light switch control-remote alarm mode settings : on, off, at home-remote lock / unlock entrance-remote doorbell camera (service, delivery interaction)-temperature & flood sensors around appropiate areas-alert capability (various) set for your concerns-ample exterior motion dection led lighting, some solar powered lights that illuminate all night-phone app that you are comfortable usingThere are more attributes I would want but I'll stop here. 

You would, however, have to always monitor payments closely and file for eviction quickly.

So how well are those houses well cared for and what type of crime and drug issues are reoccurring?

Also, you can get a wireless motion sensor security cam/monitor with phone app. and that you can actually talk into it.  

Think about how you would monitor payment and period covered. 

I have one unit that had a reoccurence after this. 

Can you devote 10 hours a week as a library monitor to get the house you want?

It connects to your wifi and allows you to fully manage remotely and monitor usage. 

OK, apparently nobody monitors this forum.I found my own answer.