Thing is about Lian Li cases now, is that the rear fan mounting hole has grommets right next to it. If you look closely at the images online, there are also grooves from the fan location to those grommets. This allows you to push the head unit in from the back, and still be able to hang the AIO externally!
Lian-Li Global | PC-Q33
Just above the video at the bottom of the page there is an image showing what I mean.