Fixed beds have the disadvantage of always being a bed; they take up a huge amount of floor space in any vehicle, but in a way this is an advantage: there is no twice-daily chore of reconfiguring the living space. Most fixed beds are placed fairly high off the floor so that the space under the bed can be used for storage or other uses. In many vans, fixed beds are placed at the rear with the space under it used as a garage for the electrical system, water tanks, and storage of any gear that is used outdoors or things that aren't needed very often.
IKEA Skorva
One popular solution for fixed beds is to use the IKEA SKORVA center support beams from one side of the van to the other. They are inexpensive, strong, and adjustable, with no need for a center support beam. Most people use 4 beams to build their bed base.
