Interesting. It looks like a variation of an external Durso. I would be worried about it sucking in air and making that gurgling sound. I think this design would require you to fiddle with it a lot.
If you would like to save space in the tank, why not cut the overflow box teeth into the back pane of glass and silicone and external box that holds your standpipe? Its a heck of a lot more work, but in the end, it will look much cleaner.
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32"x32"x20" Cube-ish tank
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