First off,
How have things faired with the existing operator?
I presume it is questionable at best because he is calling it quits.
Secondly,
What experience do you have with organic anything?
I presume minimal or you would not be asking us how to do it.
I suggest that you want to receive 10% of the proceeds that you can take to the bank.
Give the owners 90% of the income and 100% of the bills.