Not sure you've seen this Fyre, but PeteTheDuck's
Forge Quacks #20 has a potentially novel solution for making this map in the Reach Forge editor:
Stack em' shits!
Yeah, I've known about that for a long time. Honestly, it's an annoying feature of Reach's teleporters. Wanted to make something for Haloball where you got teleported back to the center of the court if you tried to go up to the capture points, but also didn't want the entrance node to be visible (and cover the entire space with one), it ends up with you getting ported into the middle of the air. It could be used to layer rooms on top of each other.. although I'd have to test to make sure you couldn't block one room from another room.
I actually considered attempting Chiron on Sandbox once, because what i was gonna do was use the built-in teleporter on the map for Forge that lets you get to the Sky Bubble to make the last porter connection. It's actually still active in normal gameplay, you just can't see it.
This reminds me. Why was forge world not included with CEA?
The more perplexing decision was the one to never have Anniversary Slayer on Blood Gulch in matchmaking. They ran out of room on the disc (even for space for the Anniversary Slayer gametype that actually lets you use the Halo 1 pistol - you have to have LIVE to download the gametype), but there was never anything preventing them from using the mode in matchmaking on the map.
So the situation with the decisions behind the CE:A disc is Reach has THE Halo 1 map that everyone remembers and loves built into it, we have a Halo 1 map pack, we have a Halo 1 gametype, but never shall you play Halo 1 mode on the main Halo 1 map in matchmaking. And due to however they rigged the Anniversary disc playlists, they can't even mark Reach disc maps as optional, so there's no way for them to have the game go "everyone here has the Reach disc, let them vote on Hem"