It might be a bit different in Darwin but you couldn't make a soft floor camper for remotely close to what you can but a decent quality used one here in SEQ. Everyone's situation is different but if you haven't done much with the trailer it might be worth looking at buying a 2nd hand camper that's already good to go. The prices they end up selling for is often crazy cheap, mostly just due to supply and demand because they seem to have somewhat gone out of fashion.