I led a group over the Rig Rd a few years ago - no trailers & traveling W to E.
The fuel figures for the group were:
Fuel Consumption Mt Dare to Birdsville 630klms
LC 200 Auto series 4.5 litre Turbo Diesel - 162 litres
Patrol 4.5ltr Turbo petrol Auto - 182 litres
LC 100 Turbo Diesel Auto - 120 litres
LC100 Turbo Diesel Auto - approx 145 litres
LC100 Turbo Diesel Auto - 121 litres
LC100 Diesel Manual – 130 litres
I hate to think what towing a heavy camper would do to these figures.