That definitely clarifies things. In that case... small first-aid kit, assorted tools, emergency shelter, thermal blankets, a few bottles of water, some fortified food (to keep us going as we figure out what to do about local sources), compass, good knife, rope, and a pistol, because why not? Compact enough to fit in just fine, and might come in handy for something or another. Small ax, too?
My backpack already contains most* of these things for when we go hiking (in large part because @Cy~ tends to be very safety-minded... especially compared to me), with room to spare, so I know it'd fit.
* I'll leave it up to your imagination which are and are not part of our regular load.