How about a small challenging & chilling smite nerf?
Everyone knows junglers have way too much time on their hands. Why not make it so that to cast challenging or chilling smites on champions it requires two charges? Casting it on monsters still only requires one.
It's not much, but one of the problems with junglers is they can camp out in a lane, storing up smite charges. They may or may not use one in the attempted gank, and then they can go through their jungle quickly and use up the second smite charge to continue with a speedy clear.