Bless my loving wife!

[mark]

For your overflow if you want quiet, might consider a Herbie style. Only being able to drill on the backwall still could be done like Reefjunkies with an internal overflow chamber or with a external chamber where you would need notch out the backwall (such as Skimmin's old tank)

If not the Herbie can still do a Coast to Coast chamber style (a complicated example) or even something just from a horizontal piece of PVC.