Found this while looking for Travel-Sleeper on the internet, because my parents also had one. They bought it in 1964 in Oss (city in the south of The Netherlands) and I always was under the impression that the TS originated there. But then I was 6 years old at the time. . Do you know if they were perhaps build under license?
Ours looked slightly different: the trailer was red, the canvas was both off-white and blue (like shown in the drawings in instructions) and the "put up" bed didn't wasn't a one-piece canvas with rings, but consisted of ribbons from a kind of pvc/plastic. It also came with a camp kitchen, which was carried on the towbar.
Over 11 years we travelled 9 years to Spain and 1 to Austria (and remained in the Netherlands 1 year as we were moving).
My father added several things, like an elevated floor (in parts) to the trailer, so we didn't need to unpack everything while stopping for just a night underway and a "frame" on the lid so we could take our boat along (SportYak of plastic).
Those vacations are among my fondest memories.
If you like, I can see if I can dig up some old pictures