Have discovered that there [u]IS[/u] an official Toyota wiring loom for mounting an auxiliary number plate at the rear, two different ones in fact. Very desirable for those of us who want to use a Curt hitch, or similar, to mount a bike carrier on. (Solar roof, so no roof mount possible). Toyota part numbers: PZ457-G0561-00 & PZ457-G0560-00. There's plainly a difference but I haven't bothered to discover what it is yet. These looms are dealer fit only (When you see the amount of stuff that has to be removed and put back, you'll understand why) and specific to the Gen3 models.
They are also specific to the Toyota 'Standalone bike holder', not for any other purpose, which has part number PZ4AP-UK944-00 for a 2-bike carrier and PZ4AP-UK946-00 for the 3-bike version. Looks suspiciously like the Thule aftermarket carriers, so it would be interesting to compare prices between the 'Official Toyota' version and those.
Since Toyota are making and selling official wiring looms specifically for a hitch-mount carriers on the UK models it must be legit to install and use the same, so long as you're not towing something on the hitch.
So, where can I get that Curt hitch in the UK, or must I order from the States?