I agree with Driftwood, I wish all my tanks were drilled for a sump, make life easier.
You can hide heaters in the sump, use filter socks below the overflow holes that are excellent water polishers, or add and hide all sorts of unsightly hardware, while adding extra gallons. Most maintenance is then done, in the sump and outside the tank proper.
You would either use stand pipes cut to the desired water depth, or dark plates set to water depth disguising the over flow holes. I'm sure one of your local fish stores would have an example.