Balancing overflows really isn't a problem. I have my dursos set at about the same height (eyeballed) and they both flow water. If one flows a little faster than the other, I would never be able to tell. You could even use one drain with a valve to feed your fuge low flow and other drain to your sump.
The main thing to keep in mind is that each overflow must be able to drain at least as much as your return pump can deliver to your tank. That way if something were to ever go wrong with one drain, your not flooding.
Like Headless suggested, you should build the extra width and out to the 24" now. It's really convenient. You will really like having the edge around your tank to set things on. Food, glue and epoxy, test kits, the TV remote and just about anything else that collects where there's room. If there's one thing I would do different if I built another stand it would be to build a bigger edge around the tank. Mine's only about 2 1/2 inches.