This is so I know if I should keep the person I currently have.

Id have a lawyer on hand, this person seems like they will escalate issues once you notify them you aren't renewing their lease.  

One-person rental units are in the highest demand, and co-living directly appeals to this market.

I can "cash flow" more from my stocks/index funds and high yield savings account with far less stress. 

.: I would go HELOC for sure that would be best as others were saying the lower cost for the money changes between paying a higher rate for a personal line and typically personal lines they want a higher monthly charge as well independent from the interest rate.  

Personally, I'd go with the As-Is scenario.

Get a copy.2) Bring your trust documents to any bank and open a trust account in the name of the plan with you and your spouse as the trustees.3) Transfer your existing 401(k) funds into the checking account associated with your 401(k) trust.

I think the 10-14% rate is where it will be for the next five or so years personally so plenty of opportunity

I spent many years managing myself and personally collecting rent checks. 

Tell me - someone selling their home to your son, Subject-To - is this a person who has made good life choices?