@Eldon HongoThe use of debt-financing such as a mortgage in your IRA is a more complex strategy, but one that can really boost the returns of your IRA.There are two key considerations:The debt must be non-recourse, meaning no personal guarantee from you. 

There are several reasons for that,   summed up they are:1)  the duplex is the oldest property (pre-1900) and while well maintained,   is economically and functionally obsolete2)  Located on L2 zoned land  (4 townhouses,   small apartment/ SEDU complex, etc) would be allowed on lot.3)  I was ready to end house hacking,  I had lived in one unit of the duplex since purchase4)  Lower unit (one I owner occupied) not habitable per Seattle rental inspection ordinance.   

@Mark GibbsTaxation on notes is complex.

My ultimate goal is to own multiple large 100 plus unit complexes. 

there are few things in real estate that are more complex than buying NPN on owner occ properties.. 

It is fairly complex, especially for a first time house hack investment.

If you are looking to wholesale these deals, just know that your buyers are going to have to put a quiet title process (quite a few thousand dollars depending on the deal complexity) into their calculations to get the property's title clear, marketable and insurable for their end retail buyers.

What if you just bought a 25 unit complex or 25 individual SFH?

He is a TX attorney that deals a lot with complex partnerships so he can definitely help.

We do not have direct experience with what is typically the "norm" at an apartment complex but I think in that case since a parking lot would be used by all tenants, then the owner would be responsible for plowing parking areas.