Is that a regular overflow? Looks like there is a gridded cutout in the middle... if it is a regular corner overflow, you can have the drain to the sump lower, to make sure the tank on the top won't overflowed. I also assume you have enough head room under the stand to work around the skimmer. With a mulitmodule sump design like this, you need more room when you do services.
It is gridded cutout in the middle... the overflow is actually the tube, thats why its so high... The overflow box is not actually an overflow but more like a cover for everything behind it.
the higher it is the lower the sump level has so the sump pump sucks air before the display floods.
also if you ran the overflow pipe down then back up that pipe would determine the display water level. You could then lower the bulkhead location then. and the water that runs to the sump is more the volume of the pipe and less the lowering of the entire tank. So hopefully less water runs to the sump under power outages.
Also by changing the height of the pipe running back up you could adjust the running level of the display. But with just the bulkhead, the location of the bulkhead determines the display pump on water level. and it's kinda hard to redrill the hole but easy to lengthen or shorten a pipe.
