Hello biggerpockets,I am trying to understand all the potential *legal* issues I can run into by trying to split a regular single family home that is zoned as such into essentially a duplex with 2 separate tenants, one living in the house and the other in the basement.

You should be able to live a couple months on a credit card or have a paid off car you can sell. 

The advantage you have living in SD for 15 years is knowing neighborhoods,which ones are improving, where you will like to live, and which will attract good tenants. 

We received the Judgment against the tenants who continue to live rent free in the property.

People need places to live and as long as people aren't moving out of the area in large numbers, run the numbers and see if they work for you. 

I have invested my life savings in real estate to earn a living, save for retirement and build wealth for my family.

The second personal residence that I bought was a two unit and lived I one and rented the other. 

I have about 60K in equity, minimal cash on hand, 3.5% intrest on the current house, and live in Tulsa OK area.

How many times have you heard somebody say some version of this statement: “We made 100,000 on the sale of our house and we only lived there for five years.

., don't forget to factor in the cost of your rent in your calculation.For example, house hacking a multifamily in a desirable part of Philly might not cashflow, but is the reduction to your cost of living greater than the cashflow from an investment property in a bad part of town?