I am currently house-hacking an upper/lower duplex and recently had a tenant turnover.

You CAN start the process and even lock your rate and have everything ready to close on day 12 months +1. 

We are seeing more vacancies, for longer periods of time, and for lower rents.Personally, I am very bullish on the Cape Coral market because the prices are lower than they have been in 3 -4 years.

You can use an FHA loan with 3.5% down (That’s $7,000 cash out of your pocket) Then there are closing costs of a couple of thousand dollars.

We purchased the property for $28,000 and sold it for $41,500 using our efficient whole-tailing and double closing process.

Are you closing with cash? 

I finally received a demand letter from a "nonprofit attorney" representing the tenant, claiming that the tenant was living in uninhabitable conditions—typical for a non-paying tenant, I guess—and now she wants to "renegotiate" the rent and keep living in the same space.She has been filing complaints with various government departments, but all the cases were minor and have been closed.

If you are investing for a return on capital, the more you pay it down the lower your return on equity will become, as you have more cash tied up in an investment that brings in a fixed income. 

My question is, since I already closed on the house, can I still do the BRRRR method?

Rent can be increased annually, but expenses also go up (hopefully at a lower rate).