If you don't wont to create a MI3a for Disney please just write a Online-Blog-Book with the upcoming story.
I wont to know whats the secret of monkey island is^^

And,... If a real Book hurts any licence we can call it "The Fanfiction of Monkey Island written by Nor Treblig" or something like that.

As long as I can read the true story befor I or you die Iam happy^^

Or even better,... Your last will are the publishing of the true story/secret.