I have received owner financing from sellers around the 5% range (but less money down).

For example, taxes were owed, improper documentation, etc.

The return was high that many retired doctors and professionals enjoyed the high interests received to live on. 

Is there an IRS document that describes this, that anyone could point me to? 

Assuming this property is not a dog house in a war zone you will need to shell out significant cash to buy it and you will receive the same rent  as a leveraged property.

At closing you are going to sign a document stating that you will occupy the property within 60 days.

Never received a 1099-S.

As I am experienced with QuickBooks, let me talk about it:Enter all transactions as you receive them and not when you pay them:- Enter all rent as invoices- Enter all expenses as bills- Enter loans, closing, etc.IT is also called Accrual Basis.

Yes, one syndicator I invested with started to provide all documents, statements, distribution history and the like online.

What they have done with the LLC is pushed the custodian into a background role - simply documenting the IRA's single investment of the LLC, doing annual reporting and acting as gatekeeper for contributions, distributions and plan-to-plan transfers.