The best marque selection tutorial

I have used this tutorial to make a marquee selection 4.23 Marquee Selection part 1 [UE4 - RTS Tutorial] - YouTube
However, these settings have a problem. If you click about 100 units away from the object it can be selected as well. Also if you have a camera angle it can select a unit that is behind the camera. I this the translation of the box on the screen to the location in the world is broken. Does anyone worked with Marquee selection for RTS games alike and can share so technics for that?
Thanks