On the hygiene, I'd consider soap as well as purell. I use purell a lot at Burning Man, but the wash water in the basin after I wash my hands shows there's lots of playa powder left on that purell doesn't remove. Wash your face and body with soap occasionally. That's hygienic, too. :-> I vote for a bar of soap.

On garbage bags as shelter/clothing, I'd thought they were last resort for people who didn't plan ahead? You list a tarp or poncho and a rain suit, so I'm missing the point of the garbage bags, unless maybe they're for garbage.