Nice Job, I had never heard of this until a couple of days ago, when I talked to the guy at Inter-American, Mitch I think. He's the guy that makes the Starphire tanks from Canada. He was trying to describe this, how the only thing you see is the cutouts. He said soon it will be the only way to go with overflows.
Now that I've seen this, I would have to agree.
I dont understand your comment about the plumbing. What is the male adapter for. I'm assuming you are putting a box behind the cutouts. What size pump will you use to bring the water back up? I guess you just need to make sure you can get more water out of the tank than the pump can bring back...Right? I would think going with (One) 1 1/2" might be better. One inch can only carry about 600 GPH I think. You probably already know more than I do anyway, so I'll stop talking.
I'm looking for a good deal on a 120 gallon tank. It Will have an external overflow like this.
Keep posting the pics.
Hef.