Hybrids in general make good touring bikes because of their relatively 'relaxed' geometry, ie comfort, and low granny gear. Augment the flat bar with bar ends and maybe an aerobar. I consider an aerobar essential on a DF for long saddle days. Great position in head winds and for hill climbing. Also, light, narrow tires for more responsiveness and therefore more fun. You really don't need wide, heavy tires for loaded touring on pavement.

A time trial bike(light, aerobars, 23 mm tires) pulling a light trailer is a reasonably comfortable, very responsive touring combo. And a fast, fun ride when not touring. If touring in an area where the climbs don't exceed about 4% grade, you probably won't have to modify the gearing..I'm 72 and just discovered this a year ago. Don't dismiss the idea without investigating it.

For ultimate comfort, go recumbent.