Similar to your "temporary poncho", this year starting on the PCT I had just mailed my windshirt home when I ran into fairly hellacious wind. Fairly quick work with mini-scissors to make head and arm holes and I used that "poor mans wind shirt" happily for a couple hundred miles or more (I got my wind shirt mailed back before it wore out anyway).

Similar to your "stuff pack in" comment, for a lot of people a trash bag is the right solution to keeping some gear out of the tent yet dry and somewhat protected from wildlife.

In wet weather I'll use a smaller trash type bag to put shoes in at night.

Living and hiking in Washington state, two or even three of the lighter/thinner black yard waste bags are just de rigueur.