be careful cutting on the support, I just read yesterday where someones acrylic tank started to bow after cutting a slot in the brace. I also remember reading else were about cutting the brace incorrectly causing bowing
It doesn't look like there's much of a brace.... 4"-5"? An AC110 will require a good size opening so it'll cut into your brace.... may be close! I've done it before with a router.... but you'll need to make a guide/jig for it. (I'd do it for you but wouldn't want the responsibility!)