Adding a second overflow?

yep should be easy.

You can add another and most lfs can order them from manufacturers or I like the options from glass-holes.com. diy could be a bit of a headache. I tried to make one and cutting teeth was impossible but I didnt have great tools

+1 on the glass holes overflow boxes/kits. I've put their 700gph kit on two tanks now.

I've never done it. but I'm thinking....it's just a drain or two and a return line in the bottom of the tank....3 holes....and then a black "overflow tower" siliconed to the back of the tank to hide the pipes that come up through the bottom of the tank. doesn't sound too hard at all. hardest part is drilling the holes probably....