The ideal fit to set up the Rev Tent for sleep in the tub of a Ute is 1220mm 2134mm (w tailgate down). But the Rev Tent will fit is narrower tubs. The mattress of of the tent is 1193mm and can be compressed slightly. There is also a bit of flexibility in the tent poles. We have seen the tent set up and working perfectly fine between the arches of a Ford Ranger (1139mm width), and Nissan Navara (1134mm width) and LDV T60.
For other utes with narrow distances between the arches, like a Hilux, Triton, or D-Max, you'd have to compress the mattress more. The Rev Tent will work, just note that the mattress may not "pop" back in to shape after use.