DIY external overflow on 20" cube

[nerdz]

Hi

I just received a current USA 34G 20" cube super bright tank. Its basically a Solana minus AIO chamber.

I want to install an external overflow box, notched coast to coast style... Hoping some experts chime in.

Wondering about:

width of over flow?
2 pipes?
What diameter pipes, 3/4"?
Water height in tank, 1.5" down (rimless tank)?
Glass thickness, 3/8"?

I know that is a lot of questions, but any input would help.

Cheers!