From what I understand, I need to hire an external company (not PG&E) to come install the meters and monitor them. 

You'll probably need to send either (30) or (60) day Notice of change of Terms and/or Notice to Correct or Quit  and or Terminate.Does not sound like an ideal rental house from an investor perspective and your distance makes management and monitoring difficult.

If he has good credit, I would give him a pass and monitor the situation closely.

The cost savings from preventing this alone will almost always pay for meters.Ryan:I am familiar with sub-metering in a variety of contexts - and have written/developed monitoring/control systems for remote management of meters.  

Let the tenants know that you have heard of some crime in the area so you are going to be monitoring.

Knowing that, they should have monitored him until he was gone.

I have similar cameras monitoring my other 10 units.

I'm going to monitor the activity of her unit for this month, till her lease expires.  

I already use Google Drive/ Work.Any suggestions for tablets, monitors etc?

Monitoring the work of a property management company would take time and energy too.