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

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

I personally would not invest in detroit as historically its not a appreciating market and for cash flow and I invest primarily for appreciation - I go off the location location location mantra. 

Share what you are looking for and the deals you are working on with your network in person and on social media regularly.2.

I'm not a professional Tax person.

Personally, I wouldn't offer SubTo or a Wrap, For reasons I've written about fairly extensively. https://www.biggerpockets.com/forums/70/topics/1227199-the-m...However, I would sell on "Lease Option" and that may work for you.

We would want to use it for personal use probably one per year. 

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

I was thinking if I can talk to my neighbor about sharing the cost (I, the landlord, personally provide labor and my neighbor provide material (e.g. fence pickets)).

He teaches people to build small, but productive, portfolios.