The fact that you are employing a BRRRR strategy really has nothing to do with the lender's appetite for the refinance. 

#2 do you have an appetite for more? 

It really depends on your risk appetite annd how much money you're looking to spend but the second strategy offers much more upside equity potential.

Drive to the neighborhoods where some of these deals are that you’re analyzing to test your appetite for “safety” or feel.

Of course, I would have to see if it pencils to know for sure, but I definitely would have kept looking to see if those numbers held up  everybody's risk appetite is different

It really depends on your appetite to get involved or if you want to minimize your guest involvement. 

General, STR lenders will tend to require liquid assets of about 6 months of payments (including tax and insurance in addition to debt service), I would say thats probably the benchmark, but you can adjust for your risk appetite

But apparently if I find this deal that fits their appetite they will be willing to work with me.

There's not a lot of appetite for "loaning you the down payment" from most lenders.

@Sol RomandThere is not much appetite for mixed use properties, in your case is especially (75% office space); business banking route might be an option; in Non QM mixed use are case by case and the rates are above 8%.