Folks, if you've recently upgraded or renewed your annual club membership but it's still not active, please reach out to the BOD or a moderator. The PayPal system has a slight bug which it doesn't allow it to activate the account on it's own.
I used a hang on back overflow for years on my 75g way back in the nineties, worked fine and as far as flooding goes that can be totally avoided with a sump that has the capacity to take the extra volume of tank water that will fill the sump just until tank water level lowers past the skimmer...