If you are looking at tangs, a Biota yellow and a Tomini would work. Despite popular opinion, not all Ctenochaetus sp. stay small. For example, my 6.5" C. flavicauda (White Tailed) and almost 7" C. cf striatus (Orange Striated) would be overly cramped in that footprint and would likely kill every other fish in the tank.
As for the appropriateness of other fish that meet your three requirements, I would look at perhaps a Dwarf Angel or a larger wrasse. For the latter, I'll tag in @Slocke.
I love my dwarf flame angel, adds a nice pop of red. I love my tomini as well.
A coral Beauty might be another good option.
Both the dwarf red flame angel and coral beauty are "Reef safe with caution", so you're rolling the dice a bit, I combat that with 3x feedings a day, and right now my dward flame angel is doing great.