This is the foundation of my internal bike storage. A 1300mm long drawer/tray that slides out full length, rated to 150kg.
The bikes will have some kind of upright and wheel trays to be loaded onto outside the van and then secured for transit before being slid inside to fit between the bench seat and the triple passenger seats in the second row without removing the wheels. This photo shows them in situ, but prior to the tray was built.
The tray will also double up as a place to store camping gear on longer trips. It means that the boxes/awning/gubbins etc that would take up space inside the van, can be slid out of the way when we stop to allow use of the bench and still have leg room. When sleeping, the bed will fold down on top of any boxes situated on the tray.
In normal use, when there are no bikes or gear stored in the back, the tray is just like its part of the floor (albeit 30mm or so higher).
More details to follow.