Great photograph. Thank you for posting it Tom.
The trailer is an Eriba Puck from the 70s. It is a tiny and lightweight caravan (600 to 700kgs) manufactured in Germany. It was designed to be towed by very small cars and stowed in your garage during the winter. They still make Eribas today, they don't look much different and are a common sight on Europe's roads.
The most recent M-B Classic magazine has an article on a tour of Germany with a Fintail/Eriba combination. Maybe the Fintail is a better choice of towcar - although the Pagoda in the photograph seems to be doing just fine.
Regards
Andrew