Route: Couple of options.
- Detach the camera, then peek-a-portal/portal stand to the end section, keeping the camera with you (this is annoying to do in real time). ABH/AFH with a moon jump into the elevator.
- ABH and place a portal underneath the “vertical platform” facing towards the elevator on the floor. Fall through this portal. Jump into the portal from the raised stairs backwards, disconnecting the camera as you’re falling through. Grab the camera on your way by, and use it to moon jump to the exit. Since this method is obviously insanely difficult, I haven’t done much testing to check how much faster it is.