ok m8 another way is to use ur spare wheels remaining holes not use on the mount get some long bolts enuf to just be a longer than the tyre u have on the back couple of nyloc nuts and a couple of wing nuts.
put 2 bolts throu 2 spare nut holes in ur spare wheel and lock tight with the nyloc nuts put back onto you mount then put ur hi-lift over the 2 new bolts and tighten down with the wing nuts the jack will tighten against ur spare tyre
hope this helps
simon