Hacksaw,
Keep thinking! When it comes right down to it, if you can't think you've lost.
I think you come across a key concept to surviving. Not only does one need to be able to do multiple things with a single item to cut down on weight or increase functionality, but one must adapt to their current situation. You never know what, where or when something happens and the only thing you will have to work with is your mind and whatever you have handy.
The word is "improvise." The best example of this is the old tv show "MacGyver." Although the show stretched the laws of physics tremendously, there was a basis in reality, as small as it was. But the concept of improvisation was/is factual.
I have to respectfully disagree on one of your points. I would say multi-tasking is a key concept to keeping a lighter pack. If I could bring all my toys without making the pack weigh 50 pounds, I wouldn't hesitate and I'd be better equipped because of it; survival would actually be easier.
Now if you apply it to things you carry on your person, it's a whole other story.
Keep thinking is certainly key, if you've read Laurence Gonzales' Deep Survival: Who Lives, Who Dies, and Why, it's one of the things he references a lot, many people's brains just shut off in a survival situation.