Just thinking off the cuff here, but if the tank is actually concealed, I'm assuming there's no icon, just like it is with the planes, right? Is perhaps the easier solution to make it so the thing on the trees that allows concealment could be made a bit higher than it is, but invisible, so the icon won't show if they're close to foliage? Or if that was made taller, would we then have invisible plane eating barriers above the trees?
Seems to me if it's obscured, there should be no icon, if it's out in the open and/or moving, icon.
Wiley.