no.4 is interesting, but similar solution was implemented in WoW during Wintergrasp battles, and unfortunately, doesn’t worked.
In fact only real solution is separation… or weaker gates to increase “challenge” of killing them
Well, it’s been tried once in WoW and it did not work very well, true that. But this is not WoW, this is not Wintergrasp, this is not Blizzard, and its years back! We’re in 2012, this is Anet, this is GW2, this is new, so yes, the chances that it might work is pretty good in my opinion.
Seperation might be an effective solution, but might also cause disturbance by players who can’t choose this freely.
(Im not native english)