Hello there. I have been a spectator multiple times, wanting to go through blocks to see things. In my opinion, GM3 should the mode for spectators. Of course, there should definitely be boundaries on the outside of maps, so they can't just leave. But, what made me think of this was when I accidentally spectated a player who was still alive, and then I couldn't get out. So, I highly recommend adding GM3 for spectators who are out of the game.