I don't think you need to isolate the page the GM is on, as he can be on any page as well. what I think we need is an across the board copy of tokens and their relative postions. so every character on whatever layer they are on are duplicated on every other page so that no matter what page the GM is on he can easily see locations. I often DM from a separate page entirely, and only switch back once something important needs my attention(traps, combat, etc) as I use tokens with names and target macros for my whispers, emas, and as so that I can easily have a multi-npc conversation with the players, or with themselves in fact. easiest place to hide them is on a separate page called... well, npcs, in my case. My point, which I almost lost there, is that DM's are not always on the playerpageid, but still need to keep an eye on it from time to time.