My wife has toured extensively solo, and she just goes to some place, picks up a crap 3 speed, and gets on the job. I don't mean a new 3 speed...
In the old days pre MTB, there were lots of touring bikes, and as pointed out above, they all did pretty well. One of the concequences of touring falling a little to the wayside is that now there are a few pretty well known options, be they Surly, Trek, or Canondale, and probably an increased number of customs. This creates the impresio that the choices are narrow for a reason (other than the collapse of the market), but in fact there are any number of sturdy bikes.
Also back then few of the components were up to todays stadards, the cheaper cranks were steel, as were the deraileurs, and plastic. Rims were often steel. We didn't have all these fast shifting alloy groupos to chose from.
It's all good.