All self-inflating mats I have seen are self-inflating in the sense that you’re supposed to inflate them yourself. [That is, the mat self-inflates a bit, but mostly you have to breathe the air in.] ...
I have recently started trying out the backpackinglight.com mantra of a tarp and a water resistant breathable top bivy bag with a waterproof bathtub bottom (basically a shrunk inner tent). Assuming ...