Bkillen, is that what they call a "coast to coast" overflow box?
Catfish, I don't think the strainers will work as well at sucking up debris as well as a retro BD cover. I've had canister filter strained inlets at the bottom of bare tanks that picked up very little, but the drilled holes on the tank shown in my first post with slightly raised covers work excellently and pulled virtually all the debris in daily, just like a pond bottom drain. Though, I'm not sure how to do retro drains with pipes going to bulkheads near the top and have it look good as well (there would be a lot of exposed and ugly pipe)
So, going back to the catfish design, let's say I went back to the idea of holes in the bottom, so I could have my lovely and effective bottom drains. Could I not modify my original picture to include the anti-syphoning tee and have it work like this: