If it is a "converted" structure, with wiring, plumbing, and other issues shared/mixed among each unit, then you need it entirely vacant to be efficient in any significant renovation.

Specifically, I'm looking for BRRRR targets to leverage renovation know-how and efficiently recycle capital.  

In terms of capital efficiency, I always advise people to start with a house hack (to leverage low down payments), but you're in a unique situation where you can live at home and minimize cost of living already.

Check all your Florida state incentives for adding an energy-efficient roof too. https://www.myfloridahomeenerg...

I would second what @Jeff S. mentioned, that true custodians are preferable to IRA administrators.A checkbook IRA LLC is an enhancement on the above structure that is generally more time and cost efficient for investors with a more diverse portfolio.

That being said, if you do possibly buy 1 larger deal with a mortgage, you can get a lot of the benefits I just mentioned, but also gain efficiency in the cost per unit, you might be in the commercial space which has some nice benefits in how you can force the appreciation on your properties.

In my view, if you already have soft commitment from passive investors (and it sounds like you do), the most efficient way to approach this would be to find and partner up with an operator who you know, like, and trust and who already has relationships with brokers as well as the infrastructure to take deals down. 

This is a very common situation - a classic path for real estate investing (and probably the best way to go) is to slowly scale via conventional mortgages in your name, but when you start to hit around the 5 property mark, you begin to scale and the balance tips toward going with alternative financing options such as DSCR loans which allow you to take risk off the table (finance through an LLC), protect your credit report (you guaranty the loan, but shouldn't hit your personal credit) and you can scale quickly and efficiently (no DTI considerations slowing the scaling process down)

As stated, it is all about pre-screening in order to make your efforts more efficient as well as avoiding "the sketch" walking through your home.Here is my system that I have shared on the forums previously.

This will help you to achieve financial freedom quicker and more efficiently than  trying to potentially time the market.