I know the temperature is good as I check it at least twice a week.

For this reason, I did a bunch of research here and online and found a great “dumb” thermostat that simply allowed the ability to set a max limit on the temperature, regardless of what tenants actually cranked it to.

Need to raise the political temperature on these folks.

I need to monitor winter temperature in several vacant properties during the month of January.  

With windchill -51F, that means you have to wear a hat and gloves ;-)I had two properties with high efficency heaters ice up on me; which is a problem, as the interior temperatur drops fast and you end up with frozen pipes.

So 75% of the thermostat is taken from the basement unit temperature, and 25% from the upstairs unit.  

In Ann Arbor, if a dwelling is cited three times during the winter by the Housing Inspection Department because the heating system will not maintain the required temperature without portable heaters, corrective action (e.g. storm windows, insulation, additional heating capability) may be required.

First thing I would do is determine if there's need for it in the marketplace and get a temperature check on the political climate in your area.

They are the same temperature inside all year round.

Can a window crack due to very cold exterior temperature?