+1 to all of the suggestions above.

I had a trailer on my trip and loved it. The downside was it made it too easy to take too many things. It didn't take long for me to start sending things home. There are a LOT of great posts on CrazyGuyonaBike.com that you can read to get some ideas, but the one thing you're going to find out is that it doesn't matter how prepared you are, there's no way to know what will pop up until you get on the bike. I became nearly obsessive planning for my trip and one day it suddenly dawned on me that short of falling down a mountain, there wasn't anything so catastrophic that I couldn't handle it.

Get on the bike, practice if you can, and have fun. Everything else will fall into place.