I noticed that most OoB glitches in this game were done by clipping with an object and immediately thoight of clipping into Seamus' apartment early. The only grabbable object in the level (that I can think of) is the power connector for the ventilation. I used it in the area and almost got through the board and into the apartment. Here's a video if you want to attempt yourself. Haven't been able to get in fully yet. Update: You can get that far without the connector. There's also a promising spot at the right edge of Seamus' door.

You're right about the right edge being promising! We've actually already found a way to clip through it: This lets us do a sequence break that skips all of rooftops!