Using Solo 401k as a private lender

[Zoltan Fagyal]

I've been reading a lot about Solo 401K here on BP and elsewhere and I see a lot of posts but I couldn't really find specific info on using Solo 401K to fund a flip.

A little background info. For about 2 years now I have been investing with a local RE professional who flips houses. I'm usually getting around 10% on my money. I'm a full-time employee and also have an LLC that now holds a rental property. I don't have any retirement accounts yet. I was thinking that I'd set up a Solo 401K and use it for RE investments. I'm also getting into flipping and BRRR but based on what I read this may not be a good idea to use Solo 401K for that.

So if I kept investing anyway as a private lender. Would it make sense to do that through a Solo 401K account? 

Second question: what if my circumstance changes and I start hiring employees in 2-3 years? What can be done with a Solo 401K?

Thanks for all your help in advance!