Mask part of mesh to control transparency via overlapping object

Hi all, I am currently working on a project where I need to create a slider which moves a box from the left to the right of the screen.
As the box moves, any objects which it overlaps/covers need to be masked out with a fade radius.
Any of the masked/invisible areas also need to not return hit events so the hit can pass through the invisible mesh to the mesh below.

Could anyone please refer me to the neccesarry functions to achieve this as efficiently as possible using BPP?