I've got a Mainstay, and some Datrex rations in my car. But, i've also got raisons, some power bars, 1 chocolate bar (morale), and some of the "Complete meal" rice/bean packets from Zattaran's. They're really high in sodium, however. After 6 months they tasted OK still. The best idea, I think, is find stuff you like, and then buy a few of those things, in different forms. Like, buy pork&rice from Zatarrans, then have a Pork&rice MRE, then buy some rice and toss it in a ziplock bag. Hopefully something will be tough enough to stand up to use. Don't forget to replace it occasionally.

As for your shelter, it's your call. I'm currently in Michigan, I've got 2 wool blankets vacuum-packed (bought some of the Ziplock-type bags from moving day). I've also got 2 space blankets. They're cheap and small, so why not? If you do get a Heatsheet, I'd suggest the 2-person size. I tried out the 1-person last night, and it was barely adequate to cover me (5'7", 165 lbs). I tucked one end with my feet, and my head wasn't able to be closed off. Plus, wrapping it around me (like a burrito), I barely had enough to completely wrap around me.

Something else to consider, The Sportsman's Guide has some pretty cheap 20-degree sleeping bags online, if space isn't a big issue.