I agree with Chris.

I assume you are planning to be on foot and in that case not every situation is going to allow you the time to simply roll your equipment and supplies down the road. I backpack alot and most of the time I live for days on what I carried in on my back. For ease of movement, nothing beats the backpack. You may have to limit the nice to haves to get everything in, but as I have seen mentioned here several times, we are simply talking survival, not setting up an outpost. So I would recommend the backpack. Then you can place the nice to haves in your car or use one of the previous suggestions. Depending on the situation you may have the time and luxury of getting it, but if not..the backpack is your mainstay.

When selecting one, if you go that route, make sure that you don't overbuy. In otherwords, look at what you have to go in it and buy one to fit. If you buy one to big then you will end up adding in some of those nice to haves and your backpack is so heavy you and your back will regret it.

Just my thoughts.