If you are looking for free models that are good, and offer guidance, look into Rob Beardsley's underwriting model or Adventures in CRE's models.

Why this unusual business model?

Let the tenant run the A/C more and pay for the juice.I don't see an easy way out for you in Florida, except to put in fans specifically designed to have their functions hardwired to the switch, the same brand and model every time regardless of price.

I know there are children that earn income that are infants that model and even 7 year olds such as Ryan from YouTube who earns millions per year.

Can you float the lose build it into your model. 

When I was at MBA in Nashville two weeks ago, the FHFA announced they are playing with a duo score model (two not three).

Age might influence your REI business model and investment criteria but it shouldn’t keep you from jumping in.

I would like to do this model every few years and hopefully have 3-4 properties within the 8 year time-frame goal of retirement and then move onto bigger and better properties. 

If your goal is to generate a monthly cash flow(looks like $3500 under an Air BnB model less your subject to PITI and he 85k in debt service, assuming you financed that also) - why not dump this deal which has 26 years of debt service left on the note and significant cash needed to do it, and go and rent a similar house which is fixed up in the same neighborhood - and then Air BnB it? 

In hindsight, one thing I didn't plan well for in my models was utilities- I didn't know exactly what they would run and didn't know how to best split them up.