Rear License Plate mount 1930

[g8kpr]

Looking for a rear license plate holder for 1930 Cadillac.  Not even sure what it should look like. I assume it should mount to the rear light somehow.  If anyone can post a picture of what I should be looking for or has one to sell I would appreciate either.

[Hilarius]

Here you have one version of the license plate mount. I know there are several.

[Hilarius]

Two more pictures.