I think a lot of people disprove as they have seen all to many times before these "city cowboys" who throw their dogs in the back of the ute got all the big roll bars and banks of spotties and the staffy or some other type of pig dog breed on the back you know doubt seen the type of peanuts im referrin to as in the ones that live 1km from the GPO in the city, it's these clowns that lose dogs off the back of their vehicles on a regular basis and because of them it is now law that dogs be tied in the back of utes.
My Kelpie was brought up travelin around in the back of a ute and like the majority of dogs loved the car it's a pack thing with them goin out in the car i can still see her now in the rear view mirror watchin the road ahead and anticipating the next corner with her little lean, anyway i think dogs on the back of the ute is an iconic thing attached to Australia as long as the dog is secured in the back (mine never was and only come out once in a near accident) i would go for it and get ya ute they are the only vehicle i own, just make sure when ya pull up somewhere it is in the shade and supply water like ya said all the common sense things and remember on a hot day the bed in the ute is gunna be real hot so i think ya have it all nutted out with the "crate and canvass canopy for shelter" get ya ute and im sure you and ya dog will love it as it is far more practical than jammin em in a car!!
Just seen in a post above "and if you roll the ute they are buggered" dead right as i was gunna mention that also in this post if it does happen and they are not tied in they can be thrown clear and it is amazin how dogs can survive this sort of thing relatively unharmed i have a few stories on it on my website ya will find link under my profile, be good to see a pic of ya dog sittin on the back of the ute if ya do decide to buy one i am sure ya dog will love it!