There has been a proliferation of these things all over the continent. I tow a folder so can do up to 80 mph easily and safely. Caravans seem to do about 55 mph and campervans less than 45 mph, so by and large they are a bloody nuisance. It may just be the people who buy them that want to travel so slowly on autoroutes, or maybe that's the speed at which they are most comfortable. Or something.
In France particularly there is the phenomenon of the campervan overnighter park. Much like a layby, the campervans all line up side by side about 4 feet apart and don't have to pay for their overnight stay. My idea of hell on wheels.
They seem to me to be too much of a compromise to be really convenient, as I can't see what they have over a caravan - especially if you tow a car behind them, that's just a caravan towing a car instead of the other way around.