I did something similar recently. A few, relatively cheap, examples to save some weight from the bike:
KCNC foam grips (very comfy) – 20g v 120g for ODI lock-ons
Nobby Nics 2.1 EVO – 470g v 600g for Nevegal 2.1
Continental lightweight inners tubes – 125g v 200g standard ones
So around 510g (over a lb) saved without (IME) any performance loss.
I was already using 1×9, but that could save some weight too if you don’t already.
If you’re riding in a group, share out the bike tools you want to carry.
Also, think hard about how much camping stuff you actually need to carry.
SDW has lots of spots where you can pick up water (I think the taps are all listed on various websites), so you shouldn’t need to be carrying too much water at any one point – a litre of water is a kilogram, so there’s a massive potential saving there.