hodson,
I'll send you an email for contact details of RCM. With regards to engines and ADR's you need some local advice. While ADR's are a national set of standards, the states may have their own requirements as to what engine you can use. Qlder forum users will be more helpful than I. Best bet is to talk to an engineer first to find out exactly what you can use. As for chassis tests etc that your engineer will need, you can get these through the engineer that RCM uses. An RCM has no problems passing the required tests in Vic. Again, you'll need to check with a local engineer in Qld but I don't think you'll have a problem as my engineer has told me that's it's one of the better chassis's that he's tested; his words, not mine
cheers and happy Christmas