So would you think more than 3 straps are needed? Perhaps the load needed to be up against the headboard or something too? 
Not the kind of thing I would like to have strapped up against the headboard - but hey, whatever takes your fancy 
No wonder they have brought out the Driver CPC
Everyone knows that needs to be in a better lorry
Either that or use a Schlitz Cargobull
tut tut… not on a pallet either 