I have a beach rental, so I haven’t had to deal with freezing temperatures.  

That mini-split runs at 450W, or 0.45KW.The downside is that as temperatures approach 0 degrees, mini-splits lose efficiency. 

Upgraded shower with 2 shower heads and independent temperature controls.

@Nicole Miller Langston summer is busier, more because of school schedules than temperature.

(REMEMBER THIS ALWAYS) You have greatness in you,(YOU ARE ALREADY CREATE LIKE THIS< WITH GREATNESS)  just like a seed. ( a seed) doesn't say I am just a seed, a seed has potential inside, it just needs the correct environment and timing and condition to become GREAT and ABLE to create fruit, It needs, Soil, Water, and correct temperature to grow (and time) .

What I'd like it to do is to interface directly with my calendar and adjust the temperature when someone leaves and again 12 hours before someone checks in.

She wants an AC upgraded so she can control the temperature?

Sometimes either the drain valve (on the side near the bottom) or the temperature/pressure relief valve (either on the top, or on the side near the top) starts leaking, and $20 at the hardware store solves that problem.If it doesn't leak, but doesn't get hot: if it's gas, and has a pilot light, sometimes the thermocouple burns out; this is a $20 part at the hardware store. 

Also would they be able to inform you as to not only the current regulations, but also the general STR attitudes in the area and the "current temperature in the room", i.e., "the winds are changing and it might become illegal soon"?

, makes sure the temperature is perfect, makes sure the air fresheners are making the house smell great, etc.When a buyer walks into you house, it should feel like a home, not a vacant house (another reason staging is so important); the first impression is by-far the most important.Good luck!!!