This model mounts the Prusa black PSU to the side of an enclosure that is flush with a surface and doesn't require the area in the back. I've used this on a MK3 and MK4 black PSU (they appear to be the same supply).

The top bracket is not required to be affixed to the supply so when you lift the top of the enclosure, the power supply will stay in place (and tip slightly outwards). If you want to secure it, print the optional clip.

The bottom bracket has a passthrough for the power cable so make sure to guide that through before affixing to the enclosure. Then mount the PSU and guide the cables in the tray.

Don't use supports on the bottom bracket, but maybe use a brim!