Delivery of the stand and the sump happened today. I could barely concentrate at work thinking about it all day.
Here's some pics. For various reasons, we ended up needing to go with a sump design that was closer to my original version, but modified in ways that make it much, much better. One thing is for sure, this sump is a beast, it's bigger than most people's aquariums! When it's running it will hold over 100 gallons of water.
The sump is big enough that it needed to be in place with the stand lowered on top of it. Thankfully everything fit pretty much perfectly.
The highest water level in the sump when it's running will be the skimmer chamber, at 18 inches deep (the skimmer will be sitting on a 9 inch stand), then it diverts in to two chambers, a smaller refugium area where I'll culture macro algae for my tangs/grow frags, and the main water change chamber (17 inches deep). Then it exits the water change chamber in to the return area, where the lowest water level will be about 15.5 inches deep. When I want to do a water change, I'll divert the water from entering the skimmer chamber, in to the back of the return chamber, It basically isolates the entire sump from the main tank, but since the water level in the skimmer chamber will never change it will just run on still water while I empty and refill the water change chamber. This design leaves plenty of room for reactors (like, tons of room), and I'll probably still have enough room next to the tank for a single reactor if I want it.