I think you will do fine. My discus have lived in bare bottom 200G with nothing to hide behind for extended periods of time and they are happy so long as the water parameters are perfect, the tank is clean and they are well fed. Some of them bicker (as always). My mated pair spawn like clockwork whether there is substrate or not, decor or none. I think the only time you will run into problems if there is severe aggression/territoriality then maybe some form of decor would be good to allow hiding places.