I have a Carradice Camper which I used for commuting. I considered using it for touring and loaded it up as a trial. Found that yes, I could just squeeze everything inside it and a handlebar bag. But that left no convenient way to carry those temporary extras from the nearest town grocery store to the campsite and also required more careful packing than I cared to do on a regular basis. Decided that rear panniers were still a better option and left the top of the rack available for any extra items along the way.