Ah that's even more straightforward then

So, especially with a standard box, the client would receive the coordinates of obscured player models for the centre of that box.

If 99% of a player is obscured, a player with a wall hack would get information a non-cheating player would not, with basically no processing or mapping needed to turn that into useful information.

Edit: FWIW I've had this exact conversation but where I was in your shoes talking to people who work in this industry, if it could be done it would be done