The solo 401k plan participant may withdraw at any time (after completing a distribution form), all or any portion of her account balance attributable to “rollover contributions” and/or “after-tax contributions.”Employer Contributions: Employer contributions are subject to more stringent distribution rules and may be distributed upon the solo 401k participant’s severance from employment, death, or disability.

Does the person have steady/consistent employment?

If your intent right out of the gate is to develop and sell, the income wouldn't be short-term gain, it would be ordinary income with self-employment tax exposure.Holding for a year doesn't matter. 

So long as the designation on that account "in your name" is a non-spousal inherited account, then it is compatible with the old employer plans. 

I have a part time job, it's giving pre-employment drug screens to people starting contract work at the above refinery.I would be very cautious about having a STR 1.5 hours away. 

They represented themselves as self-employed business person for house showing. 

If I'd have called my landlord a couple years earlier and found out he was interested in seller financing I could've saved a third of the price vs. waiting to ask about buying it 'til my self-employment and rental income made me able to obtain conventional financing.

I consolidated my 401Ks from previous employers and “pooled” them into a Solo 401K to avoid it being a non-taxable disbursement.

I have been self-employed operating under a DBA in the field.

Employed "full-time" but my work schedule affords me a significant number of days off, and I have the skills and capability of doing most renovations myself.