A quick remix of this LCD case so that it mounts directly to extrusion. It fits fine on 3030 extrusion and should do the same on 2020 as well, it's not that thick.
You need to mount this case to the extrusion before you put the LCD panel into it. Otherwise you won't have the clearance to put the securing screws in.
There are two versions: mounting holes on the underside (as pictured), or on the topside (if you want the LCD panel to 'hang' off the extrusion).