Identify your specific needs, then shop around for a pick-up truck camper that meets those needs.
Why is it that some Dopers tend toward the no-fun in cases like these?
Who, moi? I drive a Jeep Wrangler Unlimited (good for sleeping in) with a Congo Cage, and to keep weight off the axles I tow an over-built construction utilty trailer that when parked can be hooped like a covered wagon.
Why did I suggest a pickup truck camper? You can get one with all the features you had mentioned in your OP, plus fewer embuggerances in wet or cold weather. Having to fuss about in the rain or in the deep freeze is a pain in the ass.
If you want to have a bit of fun by building your own ride, get a 4x4 pickup truck that does not have a bed in the back or already has a flatbed (no problem ordering one even if there is not one on the dealer’s lot), and build away from there – some timber, some steel tubing, some diamond metal plate, and some fabric, and you’re off to the races. If you can cut and weld, you will save some money, but even if you have to hire out it won’t be too expensive. Don’t forget to lay down some armour underneath to protect all the dangly bits (oil pan, tranny pan, transfer case etc.), and even if you don’t need a snorkel, attach some surgical tubing to your differential breathers so that the lube inside them does not turn to foam when you go wading.
Sorry. I thought you were being all “Give it up and do something completely different.” 
Or for maximum fun with minimum dollars, build a moose bus.
Nah, quite the opposite. I live in northern Ontario and spend my free time paddling/skiing/hiking about in the bush, so for me 4x4s that are set up for camping are very cool.
I figure that most folks tend to equip themselves for the environment in which they will be functioning. Today where I am, it is a lovely fall day of 45 degrees F, it will be below freezing overnight, and we’ve been having rain every few days lately. We are just into early moose season, so there are a lot of hunters in the woods that you will find camped the trailheads at the end of logging roads. They tend to drive pickups with camper tops, or moose busses. When that high a proportion of the people out there drive those sorts of rigs, I figure there is probably a reason for it related to functionality, just as there is in Australia with the utes.
Photo of moose bus, please!
To the OP, check into the costs on the modifications, before doing anything. It might easily climb higher than the cost of shipping one, second hand from Oz. I’m just saying, check it out, is all.
What will you be hauling in addition to your basic camping kit? ATV, boat, canoe/kayak, skis etc? If just your basic camping kit, consider a simple plastic plumming frame that you can assemble nightly over the bed to mount a tent over, with one sidewall of the tent able to be an awning (like a Baker tent). If you need the flatbed to hold an atv, consider a 1-3/4" steel tube cage with a platform and tent on top (or canoes/kayaks/skis on top), and a separate awning extending from the cage. For the kitchen, all you have to do is bolt together some plywood into boxes/cabinets, and hinge some plywood to extend out as working tables with drop down legs. A plastic bucket that fits into a cutout in a table will do for a sink. Small propane cooking, lighting and heating appliances are readily available (Coleman for example, which has a relatively safe catalytic heater), but watch out for moisture buildup in the winter for that will reduce the efficiency of your sleeping kit. If you go out when it is very cold, consider a wood stove, for it will not produce as much moisture. For a cooler, consider something that can run DC while you are driving and propane while you are camped. Most importatnly, take care to have proper venting of the CO2 if you use any sort of gas. Depending on where you are, mosquito netting may be your very best friend. Give a thought to containment/security, for if you have a load of stuff that is easily acccessible, some light hand might just access it.
Or if you are into a bit more luxury, have a gander at what these women are up to: http://www.2womenwhitetaildeerhunting.com/Our_Hunting_Bus_Project.php .
Elbows, that link in my previous post is of a moose bus under construction. It is a bit fancier than most with the glitzy fittings, and most do not have extra storage below the chasis the way that one does because it would reduce ground clearance. The best ones are 4x4 and have the 15 feet or so of the body chopped off at the back so that there is an exterior platform for carrying moose, atvs, etc. Since used school busses are cheap as beans, and since the modifications can usually be done with hand tools and a bit of wood, moose busses are affordable. Back when I lived in London, I saw a couple in the east end. Given that it is hunting season, you might come across one of them. If you see a camo painted school bus that looks like a bunch of bubbas took a crap on it, it’s probably a moose bus. Don’t let the looks fool you. When it comes to utility in the bush, these things are da shiznits.
Do you already have a 4WD? How about a totally tricked out off-road trailer like this? It’s basically the back end of that ute on a trailer with heavy-duty axles and suspension. They have a bunch of different options.
But…if money isn’t an object then I suggest my dream rig, the Sportsmobile ultimate adventure vehicle.
Nah, it’s popular like Heiniken is popular for some parts of the US. It’s IMPORTED dontcha know.
It’s also different than the Corona I remember. Less…and yet somehow more…nasty? Watery? I dunno what, but ew.
Sorry for the beer related hijack to an otherwise perfectly good thread about utes. I have asked the old bloke that lives up my street who’s son builds them - as far as I am given to understand, the old bloke is old, and keeps insisting on trying to build me a front gate that I do not want, but you don’t care about that. In return for him not insisting on building me a front gate from bibs and bobs he’s scavenged from somewhere, I “develop” the “fill-um” in his digital camera by taking it to the newsagent and having pictures made. You don’t care about that either.
Anyway, I mentioned you to him this morning and he is going to ask his son and come back to me as to whether or not ute conversions are to be had in America, and if so who does them.
I swear by heavy duty trailers. First, they reduce the axel load on the vehicle. Second, they reduce how much I have to lift over my head to load onto the vehicle racks. Third, they can hold one heck of a lot more, which comes in handy for vehicle shuttles were we have to double up on the load so that one vehicle goes to the start of a river, while the other vehicle remains a the finish. Fourth, your vehicle is not tied to the camp, and is free to go anywhere without having to pack it up.
If money were no object, I’d go with a retro looking Tatra: http://www.youtube.com/watch?v=Qsieu7cKna0
There are some nice Tatra campers: http://www.tatratrucksusa.com/Images/Tatra%20Camper.jpg and http://farm6.static.flickr.com/5281/5376490467_fa6589c1c4.jpg
Tatras are quite amazing when it comes to off road ability – basically they just make their own roads: http://www.youtube.com/watch?v=u6xWKwo4oOo
A crap, that retro looking truck/train thingee is a Maz, not a Tatra. Pity.
i checked back to see what people are suggesting …
i finally looked at all your links… the mud crabs are amazing …i think we call them samoan crabs …
i have travelled quite a bit in australia …in a ute …
There are tray backed utilities (4wd or otherwise) and there are utes. Ute is short for utility but I would call the OP referenced vehicle a tray back utility rather than a ute.
I wonder if from a North American view point, the distinctive look might be the tray-back/flatbed itself as opposed to the walled box/bed that is normally found on pickups in North America?
Oooooooh, baby. Thanks for that.
A variety of things. Definitely canoes/kayaks. Also, at times, a wide variety of scientific instruments and supplies in addition to camping supplies.
Thank you very much! That’s awesome!
Yeah? Where have you been?
Might be a local name then, but he definitely called it a ute, so shrug.
I should add it doesn’t much surprise me that he would call it a ute because the term is definitely used to some degree for tray back utilities. It’s a vague distinction.