If the tank looks empty then why not make something cool to go in the tank? A tube of marine grade silicone costs about three bucks and rocks are so free. Go nuts.
Aren't cichlids about as dirty as fish get. *remembering the shower of scales blowing from the Oscar's gills after eating feeders* They've definitely got a large bioload and they need to be thin in a tank. At 3 inches I'm worried that 3 dwarf caccatoos might be too much for my community tank. We'll see.
I have heard that overstocking a tank will abate some aggression in cichlids but I think it was limited specific variaties in monospecies tanks. All I remeber about crowded cichlids is my brother's six inch Oscar alone in a 10G tank. He couldn't swim a circle so he'd just float in one spot all the time. When I would go to feed him he'd get so excited that he'd do a 25% water change ... all . over . my . desk ! I don't think he was ever happy here. I'm so glad my brother took him back, either to a bigger tank or just someplace that I don't have to feel responsible for that long long face.
Don't overstock, no one wins.