I would feel safe using the security deposit on smoke mitigation on turnover which might include kill/paint purchase of ozone machine steam cleaning or replacing carpet etc. remember to account for useful life if replacing.

This includes water, sewer, trash, electric and WiFi.

Guessing it's really just a bit of wall cleaning and touchups.

There is a building not in use, but is there plumbing and electric?

The place wasn't trashed, but seems like they did no cleaning when they left.

Instead of having my cleaning and maintenance crew change the door code each week, I'd like to be able to do it myself remotely.  

You need to make sure there is room on the electrical panel to add larger appliances and also plumbing is easily accessible (to keep costs down). 

Adding a nice small decent garbage can at my pool side help to keep that area very clean nad this may be a good addition for you.

Your financials don't account for maintenance, collecting coins, cleaning, or any of the other work involved.

If yours is the only STR within 20 miles and there aren't any cities or larger towns within a 20-30 minute drive, you could easily run into trouble even finding a reliable cleaning person, let alone a full-service STR management company.I would also definitely take the time to find some comps on Airbnb in the same area as yours, with as close to the same bed/bath count as yours, and with the same finishes and amenities as you are planning to put in yours.