Well I don't think it's possible for the ender dragon to differentiate campers if you do it that way, also how would the ender dragon cause lag, if it does that means that you might have your settings to high. Also as stated before the dragon would have less hp than normal, and it would not be op because your dragon would be in the open and you have to protect it, when it's just an egg you can stay at base and make a 5 block thick obsidian cube, which sounds more op?