I am a fan of deep substrate beds as I feel more substrate I have in a tank, less problems it gives in a long run specially if you dont have good filtration.
One tip is to put lava rock in media bags and use it to add height. You can use small plastic pieces and strategically placed rocks to hold the substrate as well. I am a fan of deep substrate beds as I feel more substrate I have in a tank, less problems it gives in a long run specially if you dont have good filtration.