4WD slide-on ("truck") campers for hire in Oz?

A quick google of "4wd motor home hire Australia" shows Apollo Campers appear to do sort of what you are after, they call it an Adventure Camper..,, but I guess it depends on where you want to go if they allow that or not. It's not really a slide on though in the true sense, but maybe what you are thinking? APOLLO
There's also another mob that appear to do similar CAMPER HIRE

Just make sure you read and confirm the fine print. We hired one through an online site which 'confirmed' it could be taken off road. When we got to Darwin the actual rental place insisted it could only be taken on sealed roads. It was a hilux with a small pop up internal camper.

Whatever company you purchase from make sure you read all of their conditions before hiring.

One example is at:
http://australian4wdhire.com.au/forms_file/Australian_4WD_Hire_Terms_and_Conditions.pdf

Carefully read section 20 d.

There may be others but that section may account for fewer comments regrading this particular company.

Check that when you hire one that it is covered above the windscreen most are NOT
there is a Group of motor home / slide on, owners that rent there's out when not in use I don't have there info anymore but should be able to google them

remember a full off road motor home is a hand full in the bush & it will limit you (I own one Isuzu NPS 300 with warrior conversion with A grp slide on all 6500kg of it)

Yes, definitely important to read all the fine print!

Indeed, that Australian 4WD agreement sounds rather onerous in some places. :o And when all is said and done, it might be risky to write a negative online review about them!

Candace - The only slide-on camper that I know of for hire, is the one listed below - but you would need to hire a ute (pickup) separately.
This is a fairly compact unit, only 1950mm long (6' 5") - and I don't think it could be described as "refined", or offering luxury comfort.

Mini Motorhome hire

There are sites offering private caravan hire - but I'd have to guess, that no private owner of a ute with a slide-on fitted, would offer it for hire.

Private caravan hire

There is one slide-on camper for hire on the above site, but it appears it may be the same unit, as in the first link.

Slide-on camper for hire

There is one privately-owned Hilux 4WD with an integrated Talvor camper for hire in Perth, W.A.
However, this is the same unit as available from the commercial hirers.
The private hire rate on this rig may possibly be a little lower than the commercial hirers, and the contractual conditions may also be a little less onerous, this would depend on the owners attitude.

Hilux camper for hire privately

The greatest single problem with what you are looking for, is that slide-on campers rate as a personal accessory extension for 1 tonne or larger utes, and they're not the kind of thing that hirers would be interested in, because of their much higher overall cost, as compared to the "unitised" (factory-built, dedicated) campers.

Any slide-on camper hirers would essentially be looking at having to separately purchase both a ute and a slide-on camper - and then there's the problem of hirers being careless or lacking equipment knowledge, when potentially uncoupling and re-connecting the slide-on, with potential hirer damage.
Cheers, Ron.