Sounds a lot like what I am planning. I will run a mag 9.5 from my sump, a 20 gallon tank converted to sump which fits under my stand, to my chiller to an oceans motions squirt. I am converting the 30 gallon to a fuge and since you need a low flow (around 100 gal/ hr) for the fuge I will probably run a smaller mag pump (not sure which and run that to my return. Both pumps will be run external. I will probably have the fuge sitting behind my stand so it will be a shorter run to the OM Squirt. I will be eliminating 3 mj1200s a wavemaker pro and the Aquafuge HOB and its supply pump. My goal is basically the same as yours, plenty of flow, low power consumption, little heat added to the tank and no powerheads in the tank (72 bow).
Make sure your overflow can handle Reeflo Dart pump, 2800gph. I only have 1" lines which I believe at best can provide 900gal/hr flow for the pumps.
Good luck, I will be tagging along.