Yes fit is the most important. It easier to say change to triple than to do it. Make sure you have the chain stay length to avoid heel strike on any pannier you put behind the foot. It might be easier to pick the right pannier than to change that crank. Me I'd go for bike two if it fits, and I could solve the problem of heel strike.
Clearly buying a new touring bike (even a middle price range one) is the easiest option, but even a new bike will need to be taken care of (pampered) and may have problems (not that the older bikes are immune either). If money is an obstacle work Craig's list, bike swaps and the local shops that sell used. Touring bikes are not plentiful but they do tend to get sidelined and end up for sale at the strangest times. I have a Trek 400 (triple), a Bianchi Europa, a custom McReynolds and a Jamis Aurora that are all suitable touring bikes and were all purchased for $200 - $400 US so bargains do exist on suitable steeds for the person who invests time in the search. Adapting an existing bike is smart money until you figure out what it is you really need (hey buy a bike on the road when you find it at the bike shop and ditch the old one). Good luck and stick to prefering comfort over farkles. Tom