Rotala rotundifolia (alot of people call it indica, but its almost always rotundifolia) would be fine. Its a stem plant, so you'll be cutting and replanting alot until you don't have room in the tank anymore.
I would not recommend HC unless you are going to dose ferts in the tank (potassium, nitrates, micro nutrients) because it will not thrive without ferts. Dwarf hairgrass has a better chance of thriving IME than HC without ferts......but it would do better with it.
That is if you can get atleast a 20w daylight bulb (for the hairgrass).