This had me thinking (always a dangerous thing). I have kind of decided to give this type of setup a try, but am leaning toward a bit less radical of a road bike. It occurred to me that I have a nice 1990-ish Cannondale road bike with 32 spoke wheels that needs a new fork and front rim that might be more suitable than my current road bike.

My thought is to use an ultralight (10 ounce) REI Flash 18 backpack as a saddle bag. I plan to try packing my gear in it this weekend, hanging it on my CF road bike, and taking it for a spin to see how feasible that is.

I figure that using the old Cannondale means buying a cheap nashbar carbon fork, a rim, and changing the crank for one that takes something like maybe a 42/30 or maybe a 36/24 depending on where I would be going. That would allow using the stock derailleurs and might be possible with a crank and rings I already have on hand.

Edit: Oh and I also did a quick and dirty attempt at a packing list of the gear I might take with such a rig. Note that only the stuff marked as "Carried" is included.