agreed. Oculus doesn't allow devs to access it, otherwise I'd implement it.
Closest thing is making a normal oculus guardian , just a foot inside the wall barrier, and then do the setup with the guardian on. When you get close to a wall, it activates passthrough but you can still see the game as well. It's not ideal, game falls apart if you step too far into passthrough, but might help with a tricky setup.
I'm working on a best practices guide, will post this weekend. Even if you can get a rough setup/anchor in place at first, it becomes easier to edit walls/add new sections later on.
Oculus has hinted that they may allow devs to access passthrough feeds in the future. I dunno if I'm "important" enough to hassle them, but I'll try. A mixed mode would just be ideal.