I had one once.
I took it to Qld Transport Cleveland, They gave me ($.00) a plate like a small compliance plate. I had to pop rivet it on the draw bar of the trailer. Then get a metal scribe and scratch the info onto the plate.
Brand: Homemade
Tare:
etc etc
They told me what info i had to scratch on the plate.
They check the measurements are Ok, length from draw bar to axel centres, things like that.
Mike