The problem with that own story idea I have in mind is, that it is so universal that it would be difficult to reduce the possibilities to one concrete plot. There are thoughts involved which wouldn't be popular among many people. It might go so far that people might misunderstand the book to be some kind of attempt to write an alternative story to Torah, Bible, Quran, and about every philosophical book of the last few thousand years at the same time, and even that would be but one side-story of that book.
Back to the topic, I think the credit for the longest land before time fanfiction goes to Jason. I'm not a hundred percents certain, but I think his "Battle of the Sacred Essences" is longer than any other LBT story I have come across so far. How long is it Jason?