I am another one that is very allergic to PI. My cat used to share it with me when he'd go out and then come back in and do the figure 8 around my ankles and legs......
Anyways, anytime I am outside doing a lot of clearing, and I suspect that there may be PI in the area, I am meticulous about coming in and immediately removing my clothing and washing up in the shower with tepid water AND dishsoap. Once I get a good lather on my arms, legs, face and neck, I actually turn off the water and wait 3-5 minutes and let the lather help deactivate the oils and pull them into the suds. Then I do a very thorough rince off.
I have been told that Dawn works the best, but I use whatever I have and it is a hell of a lot cheaper than Tecnu and I really think that it works so much better.