The cyclocross bike recommendation is seemly to allow wide tires. For such a low weight load I don't think tire width is that much of a consideration. There are two major types of touring bikes. randonneuring and fully loaded touring. The first, comparatively, typically has brifters (shifter/brake levers), rear rack braze-ons, no front rack braze-ons, two waterbottle braze-ons instead of three, lighter tubing, and narrower tires. For your purpose I would get a randonneuring bike, and use one pannier, or two small front panniers, front or rear. A randonneuring bike will allow more flexibility if later you wish to do more fully loaded touring (cook, camp). It will also be more considerate than a non-touring bike of heel clearance (not hit pannier), fender clearance (if wish to add), etc.