Ask George

https://youtu.be/UZg1vrvGbdE

This will take 28mm tyres and has a nice geometry

https://www.pinarellousa.com/rokh/

I just addressed this very incident in my earlier post. First, it was an aluminum steerer, not a carbon one (not that you said otherwise, but some folks jump to this conclusion). Second, when have we seen this same failure before or since in a race? Third, think about the hundreds and hundreds of other carbon bikes that have gone through those races (see my earlier post about one day classics bikes and how often things are reused). And last but not least, Hincapie had several team mates on the exact same equipment that didn't fail. And again, those cobbles are brutal. Probably worse than any rough conditions one might encounter on tour. And those guys are racing, not touring.

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.