accept the car for what it is a car missing its tag, anything else comes off as appearing as fraud.
i happen to own a rare car missing its tag also it is probably in some tag collectors shoe box or nailed up on a garage wall..
it doesn't matter to me enough to try to rewrite history and try to create something from what i think it should be. i'm just going to use a tag from another similar year car a tag is just another part to me..