I'm by no means a seasoned veteran, but I did run the PPM last year. I still wonder about this sort of thing. Last year, in my search for answers, I came across an interesting article on the Running Times website titled, "How Long Does it Take to Benefit From a Hard Workout?" by Kristin Barry. (http://runningtimes.com/Print.aspx?articleID=20421) It references Pfitzinger's take on the subject.
Personally, in the particular and peculiar case of trying to optimize training for the PPM, I think you want to develop strength over an extended period of time (more so than a typical marathon program). In conjunction with a bit of advice from the article, it would mean hit the hills are up until about 8-10 days before the race and then start to taper down.
Of course, that doesn't mean you stop running hills altogether. In all of the articles and programs I've read and analyzed, you always want to reduce volume in the taper but maintain intensity and, in our case, maintain strength. I think strength, if not utilized, goes away rather quickly. I know pure endurance will linger longer if, for example, you stop running for 4 weeks.
Maybe you could try not running so many hills and instead do some step ups, air squats, lunges, etc, but not in excess. Just enough to maintain some strength and keep a little stress on your legs.
I'm just tossing around some ideas. I really don't know what I'm doing.