I set up my 10 gallon sump a little bit differently ( for my 29 [used a bigger skimmer, ASM 1GX, so didn't have room for a fuge ])
Here are a couple of pictures of it.
As for the overflow box you are planning on using, I would suggest looking at the LifeReef one, similar design ( U tube ) but done better, I had to modify my Eshopps one so that it wouldn't lose siphon when I shut off the main pump -- the U-Tube was too short and the boxes aren't deep enough.