I believe a Rhine River Cruise was in the original plans for Germany, and there used to be wooden doors that covered where the load/unload area was (I think that much got built but never the full show building)
"The future River Ride promises to be as enjoyable as it is informative. An early concept has guests boarding a "cruise boat" for a simulated ride down the Rhine and other rivers, the trip affording a visual impression in miniature of the cultural heritage of Germany's past and highlights of its present. Among the detailed models envision are scenes in the Black Forest, the Oktoberfest, Heidelberg, the industrial Ruhr Valley... the possibilities are limited only by the planners' imaginations." –"Walt Disney's EPCOT Center" by Richard Beard