I've always liked the idea of living in a super-compact vehicle where everything you need is practically within arm's reach, so I've been looking at the latest campervan designs, which can be rather ingenious in their use of space.
Here's a couple of 5.9m-long vehicles (by Hymer & Airstream) that manage to fit a bathroom in (and sleep up to 4 people in the former if a pop-up roof is fitted):
And here's even shorter 5.48m-long, 4-sleepers (with bathrooms), by Font Vendome — the Auto Camp XL (with pop-up roof) and Bel Horizon (with 2.78m high roof):
With the "Rando Camp", Font Vendome even squeeze a bathroom and 3 beds (or 5 beds with a pop-up roof) into a 5.41m-long van.
But what I notice about all these designs is that the space for the front seats is not used so well when not driving. If they could be used for a bed, then the space currently used for a bed could be used for other purposes, or the van made even shorter. For example, if the fixed rear bed at the rear of the Rando Camp was removed, it would only be 4.1m long.
I assume the difficulty is designing a seat that can be folded down to make a flat bed but which is also still suitably contoured and comfortable for driving.
So here's my solution — a design for campervan seats that, if there's three together forming a continuous front bench, can be unfolded to make a flat bed:
Note the seat back is attached to the base by a single rotational joint, and the seats could also slide back on floor rails and rotate around to face a table.