Hailing from Germany, Good Life Vans makes conversion kits to fulfill their motto of "Every van is a camper." Their kit features a bed that disappears when not in use, something like a Murphy Bed for vans; it allows you the room to carry your bike in the back and have an operational kitchen, yet still have the ability to sleep on the equivalent of a Queen-sized mattress at night.
The system is designed around a plywood base plate that attaches to your van's existing seat mounting points in the floor. This base plate contains the hardware that allows the kitchen unit to slide towards the center of the van to provide support for the mattress.
The mattress itself is just 9cm (3.5") thick, but there's an additional system of flat springs beneath the mattress for comfort.
Perhaps the most clever part of Good Life Vans' system is that it does not require drilling into or modifying any of the existing surfaces of your van. "It remains completely free of installation marks," the company says in the demonstration video. (It's in German, but you can turn the English subtitles on.)