I ran the numbers with 20 & 50% down and it never works out.

I ran numbers on 20% down and it generates like 200-300$ month cash flow.

The pet fee is charged one time when they move in.You should consider charging a one-time pet fee and then an on-going increase to the rent.

I ran another analysis with 10% taken out for PM and cashflow comes out to 284.06 and cash on cash Return is now 9.03%.

The solo 401k name must be listed on all purchasing document. for example: John Smith, Trustee of XYZ Solo 401k TrustAt closing, you, as trustee of the Solo 401k, will approve and sign all documents and then submit them to the closing agent along with a check from the solo 401k bank account for the purchase.All ongoing expenses in connection with the solo 401k real estate investment must be paid from the Solo 401k checking account.

They also refused to insure the rental, and the person I spoke with said basically a slate roof is just an additional "liability" on the rental property.Long story short, eventually I found another company that had no problem with the slate roof and accepted my explanation of ongoing maintenance and roofer's report (which as I recall they never actually asked to see). 

Once the units become vacant, I'll need to put in about $10,000 more, so I'm looking at about $23,000 in total rehab costs.If I ran my numbers currectly, I think that if I were to raise the unit B's rent up to $520 then it would be grossing $1,040 after all the rehabbing is done.

I was a part time agent for 10 years before I became a full time agent, so my situation may not be as applicable...since I jumped into the career already with a full understanding of how to manage a transaction, and how to manage a successful business (I ran a healthcare business before going into real estate full time). 

I ran all of my numbers that night.

I don't carry any other type of insurance because there is no ongoing work or any buildings.