w/o water, you could do it in a rack top bag and a handlebar bag. down quilt, silnylon tarp, tyvek groundsheet, a can of butane/propane, a micro stove, small pot (doesn't even have to be titanium when you're on a bike!), bag of gorp, clif bars, 2 or 3 freeze dried dinners. You can use the bike as the tarp's "tent poles" and sleep like a king. Some TP and other hygeine essentials, and extra batteries since you'd be using your headlamp as a flashlight. I could get that all in bags not much bigger than what's pictured. I don't have an ultra compressible down quilt-- my summer bag is a little bulkier.
http://www.backpackinglight.com/cgi-...ums/index.html
I've gone on long hitchhiking trips ccarrying little more cubic inches than pictured.