You're on the right path, but be careful with adding rock, especially lace rock and what not.
I want to add some to my setup, but bichirs can be so darn clumbsy especially after gulping a breath and dashing back towards the bottom of the tank.
New bichirs always bump their heads on the DW in my tank, so I'm worried about them damaging themselves if I were to introduce lace rock.
I agree with Anne, Onion, and Merbeast. Once the bichirs are a decent size, they don't care to hide. All they need is a small spot to duck their heads under some shade in case they feel a little nervous for whatever reason.