That would leave her short for February and subject to termination.2.

I am looking for a single family short term rental a few blocks from the beach.

The question is what kind of tenant's are attracted to your location?

is there like a step by step guide on investing in short term vacation home in Florida?

Rents are super-high, so the chance to rent a private room for less than what your tenant would pay for their own studio or 1BR apartment would be attractive to potential tenants.However, you must figure out a way to qualify to rent the apartment yourself.  

However, shortly after beginning the rehabs, I realized they were going to take much longer than 6 months.

The tub reglazing will be the biggest cost and a shower curtain would cover the old tub from view in the short term.

Latest one I closed in July was at 6% rate and we consider the short term rental data including AirDNA, AirBNB etc while calculating DSCR ratios.

Also, there is IRS publication 527 (p527) Residential Rental Property.Otherwise in short, your rent less your expenses (generally mortgage interest, insurance, taxes, repairs) and less depreciation is your profit/loss for federal purposes. 

If a 6 to 7 figure income is realistic in a relatively short period of time, and I could really do it with 10 hours of work a week from anywhere with internet, than it would be a great investment.