I'm looking for advice on how to best outsource bookkeeping for a rental portfolio of 15 - 20  SFR and small MFH units. 

We fully rehabbed it and continue to build equity.

We are preparing our house to turn it into a long term rental unit and plan to house hack a duplex or fourplex (along with our 4 kids 😜).

Our current focus is working on 1-4 unit fix and flips, but eventually work towards being able to refinance properties and keep and cash flow them.My question is  tailored on the the way I should structure our relationship for the legal and tax base purposes.Should I secure the deals under my business and pay my partner out of my business operating account?

What they told me was, even though I think this place should get $1100-$1200 a month per unit, it was rented before at $900 per unit (well, the dad's son lived in one and he rented the other to his friend for $900) so I can only get a loan to cover 80% of that amount(or something like that).Does all that make sense? 

I am partners in 2 condo units, and a bunch of multi-family buildings and some single family homes.

No one can answer that because the first question all depends on how your basement is set up with agree (windows, doors, access) and what your town's regulations for legalizing a basement unit (usually way harder than anyone thinks).When you say join a JV, it would depend on your relationship and the asset and the split.

@Chris WilburnIf you are willing to furnish the basement ADU, you could likely get more than $1800/month rent from medium-term renters (i.e. travel nurses) in the Portland area. 

You can make a basement habitable, but not always rentable because the latter would require you to get an updated CO and convert the basement "unit" into a legal dwelling... which would mean your house would go from a legal-2 to a legal-3 fam. 

Generally, many 2-4 unit properties are not purchased for their income producing abilities alone, as much as larger multi-unit properties are.