Most tangs do need a 6 foot tank to be happy, but Kole tang would work. Hmm, a redbar anthias is really nice and can be housed by itself. It is semi aggressive but it only gets 4" long max so it should be fine so long as you aren't putting baby gobies in there.
Have you looked at a Coral Beauty either? Very flashy fish. Well actually, neither the beauty or the anthias get too big so you could have them BOTH :O.
Kole tang, Coral Beauty, Redbar anthias = one amazing tank.
Display tank - 24g nano w/ softies/montipora
I run electrical appliances underwater and enjoy injecting things with Kalk filled syringes.