Honestly I would skip the Kuhlis. I think you will be a lot more satisfied with Coryodoras Hasborous or pygmies. I am speaking from experience.
Really consider that your options are not vast. That being said you can still have a nice tank.
I would even understock the tank and try live plants.IMO,plants really finish a tank and not only that but they greatly benefit the fish in both water quality and overall environment. Try that for a month or two and decide whether or not you really want more fish in a small tank.
I suggest a dwarf theme i.e. Dwarf Rasboras, Chili Rasboras, Dwarf Paradise fish, Badis, Pygmy/Hasborous Corys.
I am definitely interested to see what you do, and hope to see pics ASAP.