any ideas to make a DI setup achieve an even IR lighting throughout the screen? as i’m doing a huge screen, i’ve got the problem of some areas having brighter blobs than others....

Have you looked at lee filters, you should take a look at lee filter soft silver reflector or its Rosco equivalent Ecolour - 273, you can line the inside of the box with this and get an even spread IR light by reflecting your lamps off this.