[Nooj]

Take loads of carrier bags, good for internal luggage waterproofing aids, keeping dirty clothes apart from clean ones, putting over your boots to get your waterproofs on more easilly, good as small bin bags for your tent, wrapping documents in etc.

Don't take a rucksack. The bike should be taking the weight of your luggage, not you, it'll tire you out in a fraction of the time. Also if you do come off, it'll flip you over and set you rolling which is how limbs get broken.