LOL, you really have become a paltned tank fiend. A dual betta hex is 1/6 of a gallon. Which, would be very difficult to control. Laterite and sand I think would work well. Plants include glosso, rotala wallichi, rotala indica, rotala macranda, ludwigia arcuata, riccia, didplis diandra. Good luck with it, its not as easy as it sounds, even if you do have everything it takes.