Doesn't even have to be on the scoreboard, could be up tin the top right or left or wherever to be honest. I just wanna see which server I'm in when I press tab. It'll be really good for when you're trying to get your friends in your server, a lot easier than checking the player list.
As for the NPC suggestion, could you add the BP NPC to the subs gas station? That way there's one at each.