If you want a more impressive display of bold plant groupings, though, I would cut back down on the number of species to about 9-11, especially since you already have several large, showy stem plants in the list such as Ludwigia sp Pantanal, Ludwigia sp Cuba, Eusteralis stellata, etc. That way, you will have larger, more impressive groupings instead of 3-4 stems per species. You also don't have to go in there pruning every day just to keep one plant from smothering its neighbor (like Tonina getting smothered by Myriophyllum mattogrossense 'green', etc) Aquascaping with a lot of species brings a whole host of extra problems beyond just not having enough space. It will also be much easier to maintain and more visually rewarding (i.e., lacking the tossed salad look). Believe me, I know.
Could you draw us a little diagram? That will give us a clearer picture of what you are trying to achieve.
If your goal is to have a collector's "aquascape," then you are on the right track.
Carlos