The x-factor tho like you mentioned is the unexpected and that's what I fear.

It is just one component of 'total return' though.

And you'll have new cracks in unexpected places, old cracks that will not close, but instead enlarge.

More importantly, make sure the property generates enough in rent to cover regular monthly expenses,  replacement reserves, and unexpected repairs.

It talks about the different components of a successful startup and how your role impacts its success.

And there is no harm done having everybody agree going in: 1) What is the goal for the property2) What is the exit strategy 3) How to split the profits4) How to track who has how much money into the deal5) Who is going to run day to day operations6) How to handle tax issues when selling the property7) What to do if one decides they want to be cashed out8) If one gets married or divorced, depending on the state - community property issues can arise, how are you going to address that9) How to take ownership - what kind of non-entity or vesting, or what kind of entity10) If you get sued as a result of the project, what are the contingencies11) If you find unexpected problems (it is real estate after all ;-) How are you going to resolve the issuesThat will get you started.

Most of these above also have a "one-time close" construction loan component that rolls into permanent financing after construction.

Prime (high demand Vacation Rental Property I want to sell them so I can retire, it is a complete Business with all components are in place, nothing needs changing just take over what I have created, I will provide full operational information, and be available for as long as needed.  

The main difference I see with tenants in this kind of area is that they are rarely able to cope with a major setback - job loss, relationship breakup, unexpected family addition.

No room for the unexpected!