Personally I don't really think this would work...
Why? because the server already have the PK system and if you don't want other players to butt in your PVP with your friends, we got DUEL or you can just go to some map where you can do your PVP thing, so having another room for you just to chill out doesn't really make any sense as we already have the room for it.
If you don't want any MOB to hit you, you can just go to town or warp to a with non aggressive mobs, if you don't want other "low level" player to block your way, same thing, move to somewhere else, because it will be just the same as what we have in for_fild.