I just wanted to reach out and see if there was another more efficient alternative in doing this.Its a high volume game. 

Alternatively, you could explore private money lenders or partnerships that might provide more flexible funding options.

Cap rate was still decent when I sold it, even at its updated value, versus alternatives.

Yes, they should be happy to do it and yes, you'll have to find alternative solutions for the buy and rehab.

In my experience, underwriting single family home rentals in California typically results in sub-4% unleveraged returns, which is awful given the alternatives. 

Alternatively, if you're wanting to do something more aggressive, you could consider a balanced fund, such as Vanguard's LifeStrategy Income Fund (VASIX), which is 20% Stocks / 80% Bonds.

Alternatively, anyone know of any genuine private lenders that are open to this?

Here in Michigan, it’s not as easy, so I’m exploring alternatives.

There are hardship withdrawal provisions and others that can be exercised if you meet the requirements. 3) If you have access to a workplace plan, like a 401k, with a Roth component, you can consider that as well. 4) If you setup your Roth with a Self-Directed IRA custodian, they can allow you to invest in assets like real estate, private lending, private equity and other alternative assets. 

Are you suggesting this as an alternative to taking a period of time to save up the capital?