This area where your home is has been vacant fields forever.

You can only prorate the primary residence exclusion in cases where health or a job transfer have forced you to move.

Where are STRs legal in Tampa though?

You are tying to separate them but keep them together where it benefits you (premium cost saving).

Thank you  Your pricing on materials is super cheap . but I am no where near the border , so I have no idea .

The unit is coming up for rent again soon and I'm wondering if I am opening myself up for a claim of discrimination with this process - where a tenant who is not chosen could claim that I rented to someone else based on their (fill in the blank of protected class)?

I currently manage my own P&L so I've got a pretty descent view of where my money is coming in/out.

Is this a unique form of house hacking, where the rental income from our owned properties covers the rent of our new rental home?

I love where I live here in Delaware County, but I also really like the Fingerlake region! 

Bigger Pockets has a special forum on creative financing  https://www.biggerpockets.com/forums/50  where asset-based financing is discussed.