But your premise is solid and doable.

Seems doable but I'd have to advertise a very competitive rate in order to fill the condo quick. 

It sounds do-able. 

Assuming this is doable, has anyone BRRRR-ed using Solo 401k funds, refinanced, and add the cash back to the Solo 401k?

If you really want to do this business without money, its doable but VERY VERY VERY difficult. 

Anyways, you guys now make two people that have told me in very short order that AZ is doable. 

That's doable, BUT it can get tricky fast: in a situation like a refinance-step of a BRRRR, the equity is depleted as part of larger plan led by the "worker"--yes, it may not appraise well--there are risks--but, if successful, the harder-to-calculate value contributed by the worker suddenly yields a large downpayment for the next property.

The units are 6 duplexes so separating them is doable to an investor for longer term gain but not in our cards because the bank loan and their unwillingness to let us pay off the loan one sell at a time until our loan is satisfied.

In my case it's my real estate agency, but it could be your day job, flips, wholesaling, or another business you start.While it's doable, I think it's really hard to quit everything and jump into long term investing full time right from the start.By building my active income first, I now have a way to pay my bills outside of my investing portfolio and it allows me to source financing easier, open LOCs, etc.Also, I've worked really hard to get my debt to income down on things other than real estate (i.e. credit cards, car loans, etc).

Living in a tiny enclosed patio is NOT fun but definitely do able!