Went past this weird white trailer thing in the evening travelling to the east coast if Tasmania after hiking around Cradle Mountain today.
My young bloke said he saw some kind of flash, so I asked about it when I reached our B&B farm stay, and they said it was almost certainly one of the newer mobile speed cameras. Apparently they tow them, drop them off on the side of the road and leave them for varying periods.
Expecting an email from the rental car mob soon, with an administration fee from them to boot.