Have you ever considered growing plants in pots and putting them in your bare bottomed tank?
Other plants that would work: java ferm, water sprite, najas, bolbitis, banana plant, myriophyllum species, most floating plants, etc.
^Sound advice! I'm working on a planted tank and My most prolific plants are in pots. Tanks not bare bottom but at most I have 1"of sand. Like mentioned above, floating plants are the way to go. Bushy roots filter water, above water foilage helps dim the tank. I recently recieved some water hyacinth. So far I've been thoroughly pleased. Will post pics later/