I've got a 40L that I'm getting ready to add to my collection. We are going to drill the back so we can use a sump. The question that I have is placement of the holes. My thought is drill both holes near the top (at opposite ends) and use a strainer on the over flow with a down tube for the fill. My wife thinks that it would be better to drill the overflow near the bottom using a stand tube and an overflow box. I realize that her way is the most common but why? Wouldn't my way be just as effective, easier to construct, and also allow for slightly more useable space?

Any and all feedback is greatly appreciated.