Well, Les shows that it is quite doable to go without most supplies and make do for at least a week in most conditions. I've considered mature ultralight expeditions to be planned survival trips most times anyways. As a kid we'd call it hitting the woods.

You might get away with that in the Appalachians, but I wouldn't try it in the Cascades, the Rockies or most of Alaska without being suitably prepared. If you do, you better be darned sure what you are getting into.