Good looking setup you got there
Hard to tell it's current position but have you considered moving the mitra a bit towards the back wall? You mentioned adding more light towards the back but with the way the rock is done you could just position the light further back. Even lower it a little possibly making a slight shadow effect at the front of tank which I think might look nice given the layout. Although I'm not sure you can make any shadows with that light
Oh and did you buy the light then? Or what's the deal as you mentioned something about "no way" but then.... there it is.