That wouldn't work as you are suggesting. To conceal something is to render it indiscernible by the ordinary public.
It could work. What I am addressing is a change to the legal definition of "concealed", not a change to the dictionary definition. There can be a lot of wiggle room in the law and we see that every day. Why not employ the same wiggle room to our benefit? Is the glass half empty or half full? Is the weapon partly concealed or partly open? It all depends on the legal definition.