Event though my STR's and MTR's are in safe neighborhoods, I chose to install cameras in order to "keep honest people honest".   

You can have a tool that monitors the same data sources as you do today, but use the newest techniques in engineering to automatically extract names, addresses and cross reference that information with county databases before streaming that information to your CRM. 

In addition, the owner of the home must not own more than three single-family homes.3) They are unable to provide sufficient documentation, such as the emotional support animal letter, that verifies the ESA is necessary for their health and well-being.4) The tenant provides fraudulent documentation attesting to their need for an emotional support animal (usually a fake emotional support animal letter).5) The landlord can demonstrate that making accommodations for an ESA would impose undue financial burden or logistical burden. 6) The animal is destructive to the property or displays threatening behaviors that could put other tenants or yourself at risk.7) The size or nature of the animal makes it impossible to house safely or humanely.

With a newly rehabbed property that might work for a couple years, but in the long run 5% is a better and more safe/conservative estimate IMO.5.

I moved here a decade ago and have been in the real estate market since so I can share data that can help you make a safe and informed investment decision.

Less people go there which means most people there are vagrants or homeless, which makes it feel (and actually be) less safe which makes the neighborhood decline even further. 

There are some simple maintenance things that you can do yourself to make sure the wiring is safe.

There are lockable thermostats for commercial use, but I can't see that working in a rental.I think the main issue will always be that any thermostat that you can set a minimum temperature in will always be susceptible to this fail safe failing, due to the possibility the tenant could change it on purpose or on accident.I'd hope in a 4 plex as long as there is no building defect to the thermal envelope that it would be difficult for one units pipes to freeze as long as the other units were occupied, seeing as they share some common walls/ceilings.

The $80,000 would make you $4000 a year just sitting in the bank while you wait for the market to settle - that return is 100% safe and guaranteed with no tenant issues or repair expenses.  

In general, that's the first time I meet the inspector at the property (I won't ask for information before he sees the house...that would be ridiculous).I think it's safe to say that the same approach with an appraiser holds as well.