Nanochromis sp. would work in that size tank. They are west African mostly riverine species so the water parameters are not as stringent. These are beautiful but very aggressive. They are a bottom dweller so your dithers need to be surface fish.
If you are wanting rift lake cichlids then I would do shell dwellers like neolamprologis similis, multifacitus, or brevis. Lamprologus ocellatus would work too but are much more aggressive.
You can do julidachromis sp together with the shellies but make sure you have a good cave structure for them at one end and the shells at the other.