Have you considered some type of Rasabora? Maybe Boraras Brigittae, or Boraras Merah. If your not familiar with these species they're extremely small, also they're tight schoolers. They're my personal favorite.
I tried Neon's in my last tank, then went to Boraras Briggitae. The diference was astonishing- not only did the Boraras' colors naturally compliment plants much better (in my eyes), but they're small size gave an unbelievably better perspective to the tank. Neons were just too big for me! (especially with your relatively small hardscape.)
My two cents, what do others think?