A programmable thermostat, receptacles that have USB ports; there are lots of things that improve your property, don't cost a lot of cash & are kind of nice to have. 

So, we know that we want to at least add some zoning control so that both tenants have some level of control over the thermostat.

Hire a good house keeper and between VRBO and the house keeper 85% of your running a short term rental are taken care of.You could hire out the lawn care too if your brother doesn't want to deal with this.I use wifi thermostats to save on electricity when no one is at property and a lock box for keys.I see you say you don't have a pool.

Rently can be nice if you set it up to include the smart lock and smart thermostat.

If you go this route hide a lockbox for emergencies.I also have wifi thermostats so I can save on electricity wen no one is there.I also have a high end outdoor only camera system that sends me alerts on motion so that I can keep an eye on who is coming and going.Once you are set up it is pretty easy to self manage.I have HA/VRBO and Airbnb and the calendars synchronize to stay updated.

Before making a no heat call please check that the batteries in your thermostat are properly installed and have a charge. 

I'm sorry, Joseph, I'm just sick and tired of 20-year-old programmers who are busy figuring out the next greatest way to post cat pics online telling me their time as investors is too valuable to do basic home maintenance for their tenants.

I am a Master Neuro-Linguistic Programmer.

@Benjamin Manibog, The choice is yours some people pay for mentorship programmes to shorten the learning curve.

If you were a computer programmer, you would want the best and fastest hardware and software available to write the programs and be the most successful, right?