A tarp is the last thing I would leave out to save weight. All your firestarting and cooking gear is going to do you no good in the lashing rain.
6 The 'elephant in the room' of survival is 'how are you going to get a nights sleep?'. Unless it doesn't get cold or rainy where you are. A tarp is your first requirement.
Apart from that just read the specs and reviews and buy light items. And a framed sac will feel like carrying a fraction of the same weight in an unframed.
Ironically sacs are one item you shouldn't worry too much about weight. Gram counting customers have got manufacturers making sacs that are too flimsy. Good names keep breaking on me. You are down to one shoulder strap, or lose your strapped on pad or sleeping bag and you can be in serious trouble.
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