Getting started with BRRRR

[Dom Nico]

If I'm thinking of getting into the BRRRR game with properties I already own, and based on various math scenarios my cash out when it comes time to refinance might be a bit tight, what are some strategies to keep the cycle going?

I have a 2nd home (inherited) I'll be renovating as a rental. Bare minimum, it'll cost $75k to rehab to rentable condition. Has a lot of work needed beyond the cosmetic. $50k is still owed on the mortgage. 

The home could fetch $1500-2100/month rent when completed. In an arm's length market the home could be valued at $175-210k after rehab. Could it be feasible to refi at a higher amount as a rental?

I have another property I'd like to put a duplex or other multifamily on after that. New construction. I don't (and won't for a very long time) have many other funds to work with beyond what goes into the first rental. Cost to build could be $250-300k.

How should I maximize the cash out when I refi the first rental? What would be your strategies? What kinds of numbers would you aim for to jump into the new construction next?