Many thanks, Graham, for a comprehensive and amusing review of the Playmobil mobile home etc. through the ages. It does, I think, pretty well reflect the real world history, too, apart from the lack of one of those trailers which fold out into a tent or caravan.
It's an interesting and unusual theme you have there.
With the sets with four klickies and three beds, the problem can be solved by "topping and tailing" the children.