Most likely at least 4 Radions. Maybe even 6 in two lines.
You tank is wide. Double row of lights would work out better, depending on scaping options. And tank is shallow. Water would be 400mm about. Any 60 degree beam from LEDS would force you to have more units. Maybe 120 degree would work, as you do not need the punch of a narrow beam. Think even 90 degree would not be ideal in your setup.
Or whichever LED option you tank, you would get better coverage using 2 rows. Even Zetlight you would use 4 most likely. Maybe Zetlight would be better, as you do not need to light up corals on the sand that would be in other systems 600 or 700mm under water.