What about ROBS (RollOver as Business Start-up)? Basically form a C-Corp, sponsor a QRP, rollover the funds from your retirement account into the newly formed plan and then use those funds to purchase shares in the company. Now your company has capital to work with without the limitations of self directed IRA’s or 401K’s and while avoiding the 10% penalty and taxes for taking an early disbursement.
This is clearly a very simplistic overview, as with any free advice, it’s worth what you paid for it!
As far as more information, I have found the recommendation from CharlesD to be a good one about a go to source:
I am still looking into this but have not decided one way or another which direction I’ll pursue.