Panniers on a bike with short chainstays risk heel strike on the panniers. Another option is is use bikepacking, frame-mountable bags. To give you an idea of practical, field-tested ways of avoiding panniers, here is an image of my current setup that I am using on tour (Taiwan, three weeks) now...

10L Topeak Seatpost bag, and 18L dry-bag on Tern Luggage Truss and Kanga Rack. I still have volume and weight capacity to spare. The bags come off and on the bike in seconds. I don't see why this would not work for placid, Credit-card touring in Europe.
Originally Posted by
Boudicca
A friend is thinking of a buying good-condition second-hand Dahon for a gentle, self-supported trip to Europe this spring. We're not planning major hills, and we'll stay in hotels or AirBnB. But the bike will need to scrunch into a suitcase (or a well padded bag) for the plane ride over, and then fit panniers for luggage for the trip.
Do you think this will work? I have a Bike Friday, and know that the travel/pannier set-up is good. But I don't know much about the Dahon.
Clues welcome.
Thanks in advance.