Elmo:
I come very late to this discussion, but have been reading your posts for years and know you are very determined and usually find a solution.
In this case, I have worked, lived, played, even had ...hmm, a few "intimate experiences" in and around poison oak.
So, that's some 42 years, if you count from about 8 years old.
The messages saying that the oil disappear after about a year or so, are true in MY experience. I can't guarantee it for you and your particular bushes. Maybe you have cream of the crop, top quality hybrid poison oak and the oils last for centuries.
But for my Oregon poison oak on MY ranch, it lasts a year or so.
Unlucky enough to "get a rash." Zanfel is a wonder drug. Technu makes a competing product that works just as well and is usually a little cheaper. But neither are cheap. A small tube of the stuff is $25 or more, but compared to poison oak misery, it's worth it. Just make sure if you buy the Technu brand you are NOT buying just their cleaner.
What you want is Technu EXTREME. You can google both Zanfel and Technu to read about them.
A trip to the doctor also works, but is even more expensive and then you get ultra high doses of steroids, which I prefer to avoid.
Finally, you'd be amazed at what a GOOD heavy equipment operator can do for you, or the suggestions they can make. It wouldn't hurt to call one to take a look. Pricewise, and misery-wise, you could come out way ahead
Tim