Connecting two trailers together

[Bush Ranger]

Did you mean the below picture? That's what I've got after google imaging it("fifth wheelers").
It's the first time I've come across that term, but the picture is not so unfamiliar though.
I've seen it,and I've seen guys modifying caravans to be able to tow as a "fifth wheeler"(assuming that's the term)
using a ute. I would say they are ok to drive anywhere in Australia, as you said above.
But, ACT classifying them as "semi-trailers" means anybody driving a one would need an upgraded drivers license to cover
that category?!

pickup-truck-and-cardinal-trailer-by-Larry-Page-980x571.jpg

That`s it dom14. LR licence would be required I`d assume.

[dom14]

That`s it dom14. LR licence would be required I`d assume.

The one in the picture looks too massive for the ute, doesn't it?
But, I bet it's built pretty light weight, and probably only fraction of weight of the vehicle.
I wonder whether occupiers are allowed in fifth wheelers like the above while it's moving.