Yes,try this one it can also be used to remove most if not all of adhesive residue after the removal of labels etc.
White Spirit (Canadian Turps) or plain simple Turpentine applied from the top of the registration plate will seep down and be absorbed by the tape/adhesive. You will then be able to ease it off using a broad flat paint scraper from the lower edge of the registration plate.
After you have removed the registration plate clean the back of it and the caravan body with Methylated Spirits,that will neutralise the oil in the turps and evaporate leaving a clean grease free surface.
I been there,done that, so this is not guess work; it does work.