What beautiful lists. The only thing I can think of to add is probably way too obvious: a phone. If you don't already own a mobile or if it doesn't travel well, I think there might be such things as disposables. I'm on shaky ground here, though. Failing that, a prepaid phone card?

(I'm totally with you on the freezer bags, by the way; they're indispensible. Michael calls me the The Bag Lady; all those bags drive him crazy. He complains every time that it's just way over the top to bring so many, but he's wrong and he knows it.)

A vacuum flask is handy to keep the tea warm for cold night and early morning drives. And matches. I don't know why, but I always feel better if I have a box of matches somewhere about.