Looks nice.
Looks like it takes a little more room in your GB but if you NEVER have to tinker with it....it would be worth it.
With it completely buried, you never intend to have to do maintenance on it?
Since that corner is for the siphon use, have you considered just sectioning off the GB and no have media in that area?
It would allow easy access just in case...
Keep up the good work.