How can I complete this quest?

I am trying to complete the Going Postal quest in KoL, and I need to talk to the woman who is supposedly at the Hippy Camp.

Problem is, I go there and I get the standard verge of war adventures, instead of triggering the one I need for the Going Postal quest.

In the wiki, it mentions that I can get what I need after I've finished the Mysterious Island quest from the cavewoman, and also that there should be someone there before I finish that quest line, but unlike the other locations, it doesn't seem to trigger.

Does the fact I am on the verge of war prevent me from getting further in this quest? Do I need to either not have the Mysterious Island quest started at all (aka not recieved it from the Council), or completed to acquire what I need for the Going Postal quest?

Yes

Once you've talked to the council at level 12, the mysterious island quest overrides all other things happening on the mysterious island. You won't be able to adventure normally there (and get special adventures like the Going Postal ones) until the war is resolved.