Airbnb really gets under my skin.

The only other things that you'll need to consider if you go this route is that the primary rehab lender would not likely allow them to hold a lien on the property AND they may want that person to be on the borrowing entity since they in-fact are providing all/most of the "skin-in-the-game".

I'm a time sensitive person.

Lots of ways to skin the cat in this game and turn key is the easiest for most people to wrap their brain around.. just like you said you were having a hard time wrapping your brain around sub too... that's only because its a fraction of the market and generally done by folks more advanced in the business like a Mike  who do real estate more for a living than passive investing  a lot goes into doing a successful sub too..

I would want to structure it where the GC would have skin in the game, and we would split profits once its sold. 

I obviously want to follow sensitive MA landlord/tenant laws, and also be a good reasonable person. 

Thats fine because they aren't putting any skin in the game.

Good luck.....and go 'skins!

Banks are much, much more sensitive to the changes in interest rates where Mortgage Companies "securitize" their loans by basically placing those loans in "traunches" that act more like a long-term bond.

I feel sometimes if tenants have some skin in the game they are more responsible.