HC will not work in a low tech tank without co2. Pygmy chain sword is one of the best low tech carpets i heard.... check out some crypt wendtii and stargrass for midground plants, then a nice big sword for one of the back corners. Also a stem plant such as ludwigia repens or rotala rotundifolia can be used for the background.
An amazon tetra tank sounds cool, maybe a couple varieties of tetra, a single angel centerpeice, and a pair of German blue rams? Don't keep crs or any type of shrimp because the babies will be devoured in a community tank.