It would never occur to me that you could mount a camper-trailer to a Volkswagen Bug, nor have I ever thought about how you'd actually enable the junction. But somebody thought about it back in the '70s, as you'll see below. It seems crazy on some levels and practical on others:
The fact that I've never seen one of these on the road--have you?--indicates it was probably not successful, but c'mon, whoever built this thing gets an A for effort.