What Configuration For 40gal Breeder Overflow and Return?

[Enigma]

Hubby and I have selected a 40 gallon breeder for a joint project (it will replace the 10 gallon in our bedroom). He'll be doing the building (including the lights), while I offer "direction."

The bottom is tempered, so we need to drill the back/sides.

I'm hung up between:

A) putting the overflow in the centre of the back wall with two returns: one in each corner on the back wall, and
B) putting the overflow in a corner on the back wall, and the return in the other corner on the back wall.

I could use some recommendations with regards to placement, and the size of the overflow and return(s).

Thanks!