The RTT is a UpTopCampers brand which is just a re-badged ARB Simpson II, plenty of people selling them over here now and a lot cheaper than the ARB ones
I'm in Sydney, only 20km North of the City, a long way South of Cairns. The climate here is pretty mild though and my backdoor opens on to a National Park so plenty of ferns etc around the place, it was 39c here a couple of days ago, 46c is the hottest I've seen at home though!!!
I'm off to Cairns this September as part of my trip, its basically the jumping off sport before I head further North on and to the dirt. Cant wait, I've been to Cairns a few times and it a nice place but so humid.
Cheers
Steve