Hide away trailer hitch

[Kiwi]

A while back I saw a photo somewhere (but now I don't remember where) of a mod that allows the rear license plate on a 1967-1972 C10 to fold down to reveal a hidden Class III trailer hitch.

Is there an aftermarket kit to do this?

Does anyone know the low-down on this upgrade?

I'd like to perform this trailer hitch mod for my 1971 C10 and would prefer to buy a kit rather than fabricating a system myself.

Thanks for your help,

John