Some other things that might help: programmable keypad locks for remote entry (I use Schlage locks), HVAC system that has an app where you can control temperature when no guests are there, and reliable internet.

I finally gained entry to the house and the temperature was over 100 degrees.

I came from Kentucky so any temperature above freezing is great in my book.  

It’s generally a problem in winter when a small apartment is fully sealed, having a temperature of 72+, and cooking is in progress.

They will continue to fall with the temperature.   

Regardless of the system they are temperature sensitive, so you have to treat them like a computer.

If not, think about installing landlord friendly thermostats that max out at a certain temperature then drop down over a few hours.

Most experts agree that anything below 120 degrees creates a risk for bacteria to develop inside your water heater from stagnant water, such as legionella that causes Legionnaire’s disease.How to choose a temperature:  https://www.gopreferred.com/blog/what-temperature-should-my-water-heater-be-set-to/

For example if your thermostat is in a cold hallway, you can tell it to use the master bedroom room sensor to set the house temperature.

Do you leave it unlocked so guests can set it at any temperature?