Yes. Why not.
I have more concerns with cars in Brisbane then the concerns I would have meeting one of these on the highway.
If it was engineered right (dual axle on engineered and certified front trailer and independent electric brakes setups on both trailers (so braking can be adjusted for each trailer) and the driver passing a road train test then why not??
I reckon simply towing any trailer should be an annex on your license.
I can't simply chuck a trailer behind my MR license and off into the wild blue yonder I go....so why can some shmuk simply chuck on a trailer behind their car and off they go??
The number of people who cannot back a trailer is horrendous.
What's the difference in not been able to back a trailer to not been able to back a mini road train?? It's a wonder someone hasn't called them a MRT. Or SMART (stupendous mini articulated road train)