smaller reef tanks are harder to maintain, as minor changes in the water chemistry are a big deal. with more water volume, these changes to chemistry are diluted and thus have a lesser impact on the reef system.
Is it a 33 gallon bowfront? I ask because that's a weird capacity, and most 30gallon tanks are 30-36" long. But, in short, yes you could put the coralife fixture over the tank. 4wpg is enough for several types of soft corals like mushrooms.
Former advisor and planted tank geek...life's moved on though.