This is not something I've ever done before. I love to camp - we went on camping trips every year when I was young, and I take my kids on at least a couple trips every summer. But when I say "camping" the assumptions made are a) it's warm weather, b) I pack lots of stuff in the car, and c) it's at a state park or somewhere similarly well-organized. For this overnight trip we were each expected to hike a couple of miles uphill all the way while carrying our own food, a gallon of water, sleeping gear, and very warm clothes (forecast of ~20°F that night).
So I approached this almost like I would approach designing a new test: look at previous designs, step through the new test algorithm detail by detail, examine my constraints and design with them in mind, and finally buy the equipment I need. I started with the list I usually use for summer camping trips. I shopped around and bought a good internal frame backpack with plenty of room for a sleeping bag, clothing, water, etc. I did a preliminary pack of what I had to see how much room I had left. Then I went through a mental checklist of what could go wrong & what I would need if it did. Finally, I went out and bought the remainder of my equipment.
This level of detailed preparation paid off. My folding saw came in very handy cutting the wood we burned for heat that night. I stayed nice and toasty with my thermal underwear and sleeping bag (rated to 0°F). And my spare plastic baggies were invaluable in making the chocolate pudding we had for dessert.