The fact that you can buy at a discount through QBP (Salsa or Surly), Scott or Rocky Mountain is pretty important. You have at least 5 good options without going for an all-out tourer:

- Salsa Pistola
- Salsa Casseroll
- Surly Crosscheck
- Rocky Mountain 'cross bike
- Scott 'cross bike

If I were your age and size I'd seriously consider trying to make this work with the Pistola, which is a pretty interesting bike, IMHO. If you can follow some of the gear-hauling advice above (seat bags, handlebar bags) and are willing to travel really light it would be a great bike to own after the tour is over as well. Another option that people use with lighter-weight bikes is traveling with trailers - the Bob or Extrawheel, though that might be overkill for your trip. You can read up online about the advantages/disadvantages of traveling with trailers, but one of the advantages that might be attractive to you is to that it gets the extra weight off your bike's wheels, so you could take a trip like the one you're planning without having to worry so much about getting a heavyweight set of wheels for the bike.

If you get the Pistola, even traveling light you might want to consider outfitting it with a triple instead of the compact it comes stock with. And see if you can put on bigger tires - like 28c's.

Just to be clear, though - I think w/a bike like this you are emphasizing the "fast" and "light" vs. the comfortable - the Casserroll would be cushier (and a bit heavier), the Crosscheck even more so, especially cause you could increase the tire size to 32's or larger.

Full disclosure - I don't have any experience with a trailer, but have looked at them for shorter tours using a bike kind of like the Pistola. Have read a couple of online journals written by folks traveling with lightweight 'cross bikes using trailers and it seems like it might work for you if you want to ride a lighter bike, haul stuff (and deal with a trailer, which has its own set of advantages/disadvantages).