So, I just now realized I never actually had to follow the sneaky detour out of the warehouse. On my first playthrough, I played a gangrel and rushed in, making a big mess, so once I planted the astrolite, the Sabbat vampire bursts through the door. I figured that was like a scripted boss and that was the way I was supposed to take out. My second playthrough was a Malkavian where I stealthed it and found the way in through the ceiling.
Every playthrough after that, I've stealthed it and followed that same path out. On my currently playthrough (haven't played in a while,) I couldn't seem to get out of the office undetected. I'm sure I used to be able to do it, open the side door, go back and grab a cup and into the side room before the door closes, throw the cup to distract the guys, and sneak out down the stairs. This time though, one guy wouldn't take the bait and I couldn't get past him. Reloaded a few times, then I realized I don't have to do any of that. I can just run out through that big open door/window overlooking the train yard and rush for the station, in and out in a couple of minutes. How come I never noticed that before?
It's like when I realized you can see the sarcophagus on the Elizabeth Dane through the security monitor so you never even have to step on the deck, after all those times I thought it was a stealth level and I had to find the right route to avoid getting caught. (Usually I couldn't avoid the guards by the door when you go back in so I'd just have to jump off the containers and run past them. Not perfect, but you still got the extra XP for not killing anyone.)