You do NOT want use traditional Fannie Mae/Freddie Mac type of loans because they have way too many restrictons!!

I know that it is common practice to use HML for financing flips, but what are the draw backs of using HML to get favorable pricing on a buy and hold then refinance to traditional financing right after?

I know some people say the traditional "WE BUY HOUSES FOR CASH FAST" kind of stuff is played out.

It was also nice being able to work with the occasional listing or traditional buyer and collecting a normal 3% commission on those as well. so think of what you could do to help and investor while also learning and stacking cash Your future self.

Here is one that I think is very helpful: https://www.biggerpockets.com/blog/the-traditional-llc-vs-the-series-llc-which-is-better-for-real-estate-investors 

To clarify, I have converted previous 401k (previous W2 employment) to Traditional IRA to now a solo401k for our business.

When you say you don't want to go conventional, do you mean you don't want a conventional loan, or you're looking to avoid traditional bank financing altogether? 

They can give you a general preapproval based on that, but since there are more parameters such as actual rehab costs, a HML Preapproval, which is what you need, is less reliable than a traditional preapproval.

Ultimately, this may work best because it will give you the freedom to rehab the property, stabilize it and then convert to a more tradition mortgage.

My advice if you go multi unit is to go traditional multi unit.Good luck!