I am planning a trip next year to hike across the Sierra on the High Sierra Trail from Giant Forest to Whitney Portal. The last night will be near Guitar Lake and we would probably summit Whitney on our way out the last day.
I was long under the impression I had to join the Whitney lottery to stay in the Whitney Zone on that last night and to dayhike out to the Portal. However, over on SummitPost several members who have done this trip said the Whitney permit was superfluous. One even provided a link to a map that suggested Guitar Lake wasn't even in the Zone:

So I am trying to get some more advice from other quarters (I will also be asking the ranger about it when I am in Lone Pine this weekend). Can anyone refute or confirm the information I am getting from SummitPost?