I'm interested in your advice on entity (or no entity!)

No experience with the 2 you mentioned, but I'm a fan of paying the year so I don't forget next month/quarter and the coverage lapses.

It sounds attractive because everyone says it is low- or no-money down, but if you don't have money to make the deal another way, you don't have much leverage to make the deal the way you are suggesting.Sub to and seller finance are shiny objects for people who want to get started in investing to make money, but have no capital.

Agreed with Account Closed - putting real estate, or a real estate partnership - within an S-Corporation provides effectively no value, while creating significant headaches and tax consequences.The only real benefit left for an S-Corp is partial shielding of employment taxes - but a rental property already doesn't produce any self-employment taxes, so the one benefit already doesn't apply to the rental.Then you have problems with not getting basis in the debt of the property, having a lack of flexibility on future structure, issues with distributions in excess of basis...just nothing about it is good.If the Partnership hires a property manager, and that property manager ends up being your S-Corp - great, now you are perhaps better managing your exposure to self-employment income as a result of these property management fees. 

I had a FL rental that would sit vacant in the summer because no one wants to move in 100 degree weather. 

I'm buying all cash, no loan.

We are retired so no concern on the W-2 side.  

No, not your buy box, your ARV exit picture. 

Can I just increase the rent to some unrealistic amount (there's no rent control in my state)?

Interest rates priced buyers out of the market because the returns no longer made sense.