Yup, R. macrandra should fit in this tank. Thanks for the suggestion
Mayaca fluvatilis is a nice plant but I'm not sure the placement for it. At the center maybe?
Hmm. Maybe mayaca fluviatilis behind the L. arcuata and kinda in that back left corner? Then maybe R. macrandra just to the right of the mayaca, kinda next to/behind the largest stone. Might make a nice focal point.
You can get mayaca fluviatilis to form somewhat of an unkempt-looking bush with repeated trimmings as well as planting 3 or 4 stems together (in the same hole), just make sure you keep up with ferts so the new growth after successive trimmings doesn't stunt. I've had it stunt when I've slacked on my dosing following heavy trimmings, then it takes it a couple weeks to get growing nicely again.