The only fundamental piece of logic that needs to work with this system is that your drain capacity must be equal to or greater than (hopefully greater than) your return pump volume capacity. This way, you can never pump more water into the display than can drain out (no overflowing).
The holes are drilled (on cernter) about 4" below the water's surface, however, the strainers are angled up so that the actual water surface never goes below the strainer, which are positioned about 1" from the surface.
Our (100g) sump is kept at a level low enough so that when the return pump is turned off, all the water than drains out of the tank can be held by the sump.
Logan - I knew you didn't mention drilling for that very reason - I would suspect that the issue of moving the tank would be minimal compared to drilling it.