If you really want a 3-unit id talk to an architect/lawyer and seeing what could make it up to code would be a route but realize it could force you to add a sprinkler and fire monitoring system. 

Also includes time tracking for your REP status monitoring

Our reservations dept monitor each reservation to make sure it is signed. 

I've seen several in the $200-$500 range that get installed where the main water supply comes into the house, then monitor water flow and send you an alert (via text, email or whatever) if they think there may be a leak.My main goals are to detect pipes that burst during freezing, as well as to detect running toilets or other small leaks that my tenants don't bother reporting before they cost me hundreds of dollars in water bills.I'm wondering if anyone has used one of these systems and how well they've worked.

Another thing is to monitor fire insurance and liens.  

Zapier also monitors my sign now account, so then it triggers sign now to send out my rental agreement.  

And we use Minut noise monitors.

He reports that down the line he frequently gets reimbursed (it may take several years so he continues to monitor when he must renew a judgment) when a former tenant wishes to make a big item purchase such as a house.

I have 4 rental properties I want eyes on without having to pay for someone to monitor it every month or to have wifi connected with it.

Because I (I, meaning as a lender) monitor the property for taxes to ensure they are being paid (Assuming I'm not paying them through impounds).