My concept is: I take the same stuff as if I were backpacking along the same route.
But I'm a minimalist.
The first couple of days, you'll look down at your bike and say, "Look at all the stuff I'm taking with me!"
The next couple of days you'll look down at your bike and ask yourself, "What is all this stuff I'm taking with me?"
On day number six, take all the stuff you haven't used yet and throw it in the garbage can.
Enjoy the rest of the tour.