a friend of mine hooked something up like that himself, put the plate on door hinges, put a magnet on the back of the plate and on the undertray of his undertail, and had a wire going through the bike on his handlebar, so when he pulled the cord it would pull the plate up and make it stick to the magnet so you couldn't see it

where i have my plate mounted right now if a cop was to come after me he wouldn't be able to see it anyways