ay crook, i have a (probably stuffty) idea: a mortar marker/radio.
you can use it at any distance, and it marks the hitscanned spot for teammates currently sitting in a mortar for 10 seconds. people in mortars see a line, through walls, from the ground up, as well as the required angle, and rotation to hit there. you can also right click to show it to yourself and no one else too, allowing mortar users to quickly judge distances.