Yeah, the heater can be dangerous, but if I was shivering , I'd probably wrap it in something (like my dirty socks maybe) and do it anyway. At the very least, you can use it as a hand warmer.

Another easily availible thing I thought of is MRE peanut butter packets. They've got a lot of calories in fat and protein,so you won't have a big crash after the energy runs out. A couple of packs of peanut butter will do you more good in the short term then fishing and snaring supplies. You can also get Hooah bars, but then you'd have to pay for those.