Is it possible? Sure. Would you want to? Probably not if you're loaded. Most of the bike's weight isnt' in the frame anyway, it's in the components. You could take a touring frame and put ultralight wheels and parts on it, but would it be reliable? Would it be comfortable? Would it work through the mountains where you need low gears? Too much to take into consideration to say one way or the other. Same goes for carbon frames with touring wheels.

When I did my first 200K brevet, there was a guy there with a carbon something-or-other, around 15 pounds. He was a big guy... mostly muscle, but still much heavier than I was. I was riding my 35# LHT. I asked him about how it felt, and he basically said "the bike is designed for racing, I can't ride it at a leisurely pace because it gets very uncomfortable."

Coincidentally, there were guys there with faired recumbents that outweighed me by a long shot, and finished waaaay before I did. I think aero has more to do with it than bike weight, honestly.