No reason it can't work. Random things to consider:
- Flood prevention (always the biggie) - this only has one drain so I'd want some pump shut-off protection (or another drain).
-Surface skimming of display tank.
-ATO I believe has to be in DT (the baffle for the return section is only to limit amount of water it won't vary)
- Filter (sump is now technically the DT) is visible, make sure it can stay attractive (if that's important to you) and easily cleaned (limit baffles, hide sponges/socks). My sump is nasty but I only clean it monthly (really deep clean - 2x a year maybe - not my favorite job).
My best solution to the above always came down to having a large box in my display for the pump, ATO, and surface skimming (in which case, why not just go in tank/hob).
Always turned into a value prop. Am I really getting something that's easier and adds what I need in filtration over other solutions. Never could get there but I had option of sump under tank.
Good luck with your build!
