It's like The Camperbox read my mind. I was just talking about sleeping in a van down by the river. But it was in reference to Raptor's Platform XL fishing boat, what I consider to be the water-faring version of a van down by the river. The Camperbox is the literal interpretation, though: an ultra-portable travel kit that its creators say will "transform your car into a hotel bedroom in less than 30 seconds."
Adjustable to fit many cars, SUVs, and vans with collapsible backseats, The Camperbox is a sort of bed frame / flat platform with space for a foam mattress and sleeping bags on top, and storage underneath. It's intended to be light enough to pack into a bag and move easily in and out of your vehicle, but sturdy enough to support the weight of 2 sleepers with a solid and consistent surface.
The Camperbox's width is static at 90cm (35.4") but its length adjusts between 90cm and 180cm (35.4" to 70.9") to fit the size of the vehicle you set it up in. Here's a GIF.
The Camperbox seeks crowdfunding here on Kickstarter through April 29, 2017.