You're challenge will be finding someone reliable who will pay the rent on time and not cause problems or hassles for you. 

You need to think about not just the potential income but also the potential problems such as city ordinances, state law, insurance, potential eviction issues, etc.

If there were a tech solution that solved the security problem or a human solution (licensees whose sole job was to open doors), that would be a positive, time-saving innovation.Again, for the many'th time, your referencing EXISTING things/business's as-if your planning to "invent" what already exists....... https://showami.com/ 

Eventually I had problems with Regions getting wires out on a timely basis.

If DTI is a problem for a new investment property loan but you have everything else (credit, downpayment, etc), then DSCR loans are probably an excellent alternative.

Ive owned a property for 16 years with almost no problems. 

You'll run into DTI problems.

You’ll have to be very lucky or willing to buy a problem child property and/or neighborhood.  

The plumber will likely have to cut open the ceiling to confirm and make repairs, so you can save a little money by learning how to do that yourself, confirm the problem, and then call the plumber for repair, then patch the ceiling yourself.As Jonathan is trying to point out, it's important to expect these things and have funds on hand to deal with them.

I am not seeking to charge each tenant, only seeking to remotely monitor each buildings water usage to identify costly waste/problems early as possible.