I laid my hi-lift flat across the wheel wells behind the roll bars and against the tail gate. If you have the extreme 48 it literally fits perfect, I wrapped some duct tape around the bottom of the roll bar to protect the paint and that's it. Oh, and get one of these Prothane Jack Handle Grabber
It'll hold the handle in place and butt up against the tailgate so nothing rattles. Can get ya pics if you want. I have a duster cover on the back and it fits over it. For the trail, I mount it outside for easy access (I don't have alot of storage room at the house so it travels with).
Alternatively, mount the jack vertically to the roll bars using some exhaust clamps (TONS of examples of this) and then get something like this Hi-Lift Jack Mounts - JeepSWAG
for your shovels, etc..