Sump or no sump? Im assuming you have one with that size of a tank. If you do then you can have both by installing a filter sock for mechanical filtration. The rock will be your bio filtration and your skimmer will dispose of organic waste. For that size of a tank, i would invest in a huge skimmer. It will help keep your nitrates down keep your water clean.
Those Hawaiian dragon morays are crazy looking! My LFS
has had one for sale for about a year now. Theyre selling it for $500-$600. I always have to give it a passby everytime im there.