my 650ltr layflat tank is not secured.
By that I mean no straps or cage.
Its wedged very snugly between the wheel arches (peugeot swb expert) and up against the bulk head.
It took a lot of force and patience to get it in there and it definately does'nt budge, not even a mm ! would take a lot of effort and leverage to remove it (I should know I have before to protectakote the floor)
Its also baffled to the brim with about 25 meters of coiled perforated land drainage hose
I know many of you are going to disagree but hey ho my choice