I know this is a sizeable long shot, but I am seeking info on any web sites or forums connected to the above subject. The reason for this request is a personal one. My Son is Cycling from Perth to Sydney through the Nullarbar Desert in September. He is pairing up with a fellow brit, to raise money for The Joshua Foundation, which is a childrens charity. I am trying to contact Australian Truck drivers, particular those who drive Roadtrains, who whilst travelling close to the route keep an eye out for these heroic brits.
The best way would be to contact companies that run those routes, a few clicks of the mouse and you’ll find out who they are 
Good luck
Hello Lightning, I would be very surprised if any road train drivers stop to to say hello to the boys on the bikes unless they are in a parking area. In fact it might be a good idea if they moved off the road when they are about to be overtaken by them. You can try these people, you never know they might even make a donation to the charity silklogistics.com.au/contact/main/
I remember that Bunker and W.A. Freightlines in Perth used to go across every other day and it seems that they are part of The Silk group now. 
Or you could try Scotts Transport and K.S. Freighters in Mount Gambier in South Australia.
The lads should be O.K. there are plenty of Grey Nomads crossing The Nullarbor this time of year as it’s not too hot. The Grey Nomads are loads of retirees travelling around Australia in motorhomes and towing caravans and I am sure that some of them will stop and make sure that they have plenty of water and they might even cook them a meal.
The police do patrol the area but a word of warning tell them to get rugged up at night as it gets bloody cold and don’t encourage the Dingos by feeding them as they can get quite nasty. It might be a idea to stick a Union flag on the back of the bikes and be aware that the roadhouses are very few and far between.
I hope that this helps and that they make a lot of money for the charity.
Regards Steve.