He may need to try to find a hire depot that has some mine spec vehicles, and get one of those.
I know when I worked with Hertz that we had a Navara, Pajero and Patrol, all with towbars - the Navara was a full mine spec ute complete with ROPS and lights.
Be prepared to pay for some extra K's; if you know it's 900km, specify when you book that you're doing say 300km each day over a 3 day hire and that covers you for the 100-200km daily that is normal.