Lol... there are much easier solutions if this is your intent... Sev. different sites sell hide-away liscense plates that basically drop down when you want them to.. Although it sounds like a moving vehicle violation if you ask me lmao.

Just curious... Whyyyyy do you want this? lol?

Kolme

Edit: Also... remember that the law says you must have a light source on the plate during nightime... So putting it under your wing would obviously create a bit of a problem..