Partnering solo 401k with Hard Money and prohibited transactions

[Stephen R.]

I'm looking to partially fund a fix and flip using money from a self-directed solo 401k. My thought is to purchase the property using hard money and then fund the rehab, which exceeds the purchase price and current value, using the solo 401k.

1. If I used personal funds to make the down payment and pay closing costs, would it then become a prohibited transaction because of commingling? Would I have to use funds from the 401k to fund the down payment and closing costs as well? Could I use private money to cover those costs? Could I use funds from my corporation?

2. Since the hard money lender will require me to personally guarantee the loan, will that make it a prohibited transaction? Or do I only have to offer the solo 401k loan as non-recourse? 

3. Can the property still act as collateral to the non-recourse 401k loan if the hard money lender holds a first lien position? 

4. If it is possible, how would I structure the deal? How is title held? 

5. Although it would not be possible given the circumstance of this transaction, would a better partnership be to fund the purchase completely with the solo 401k and fund the rehab, either in total or in part, with hard or private money?

6. As a licensed agent would I be prohibited from acting as the agent on either the purchase or the final sale of the property? Would that make it a prohibited transaction because I "personally benefit?" What if I handled the transaction but didn't accept a commission?