I don't know too much about spilos, but most fish like places to hide, driftwood is always good, and also plants - if they do eat them, it shouldn't cost too much, what harm is done?
or try fake plants.
You could try driftwood or a similar alternative but, I'd try a bare setup with just gravel for the territorial issue to die. I tried it with my reds and they all seemed better. With a bare setup, the p's will usually all shoal more.
amazon swords are easy to keep alive with decent lighting, plant it heavily with real or fake, they wont bother your plants much I doubt, driftwood and rocks are great too, with Spilos you want to make as many obstacles as possible that way its harder for them to bite eachother
if you want that natural look go with a sand/gravel mix ( gravel keeps the sand from stirring up to much) and grow a nice carpet of java moss with some driftwood for highlights, Im experimenting with water sprite now to provide that over head cover and security that Ps absolutely love.