Exactly as Matt says; run them in | | | | configuration. Not overkill to use 4; I will be using THREE over my 30" tank (thats length!) so 1 radion for each 10 inches...not the 24 inches quoted by the manufacturer. Just pick up a use Gen 2 Pro or Gen 3 Pro for a little more.
My buddy has a Giesemann tank which is exactly your tank dimensions...his SPS colours are very nice under the Radions, but I've measured the PAR levels and I know he needs another unit.
The 24inch area is fine for mixed reefs/LPS/Zoa tanks.