Have you ever been backpacking? If so, then you just pack the usual Stuff on your bike instead of your back and off you go. (I know, the most frightening words in the English language are "All ya gotta do is . . .")
Lacking that experience, think light. Bike clothes (which can be rinsed out and re-worn), tent/tarp, sleeping bag, cooking gear and a rudimentary bike repair kit. A spare tube, pump, patches & tire irons for sure, then a small screwdriver & a 3-in-one allen wrench works for me. Oh, and if you are going with someone else, one set of tools is enough. You can share. For a short tour like that, don't take an entire Middle-of-nowhere full repair kit. You probably won't have the time for small problems to become big ones - and you're thinking light.
I like a set of off-the-bike clothes, especially dry socks and bra.
For some exhaustive and comprehensive lists, check out CrazyGuyOnABike.com. Many of the journals have great lists. You don't have to take everything, but you'll get an idea of what others take. The lists are generally in the first few pages of a journal - if it has one. You might also consider checking out the wrap-up pages in those journals, which often talk about all the Stuff they sent home or hauled along and never used.
Oh, and one last thing: Whatever else you pack, please don't forget your sense of humor and spirit of adventure. Those are the most important things you will ever carry along.
Give big space to the festive dog that make sport in the roadway. Avoid entanglement with your wheel spoke.
(Sign in Japan)
1978 Raleigh Gran Prix
2003 EZ Sport AX