Oh c'mon - you can go without a bag liner! Like, how dirty can your bag get, really? Put on clean socks before you go to bed. And, when you get home, Just hang it on a clothes-line for the afternoon. Ditch it!
And the water pump. You should ditch it! It's a FULL POUND! I have gone 30 days in the deserts of southern utah, and I've never taken a pump. You'll do fine without it. No foolin'... The one thing I do take in the desert is a little cup to dip into the puddles and seeps. Cut off the bottom of a little soda bottle (0.3 oz, the lightest!)
Is the water cloudy? Ahh, so what. Or, just take a hanky and pour the water into the water-bottle thru the hanky as a simple filter. (and a hanky cut in half works fine). Or, better yet, use your mosquito head-net! (see below)
For desert hiking, just take a second platypus as an extra vessel.
Now - A simple mosquito head-net weights 0.4 oz, and you could wear that at night. Are there any bugs to deal with, really? Thus, you ditch the bivi-sack.
- 16 oz water pump
- 10 oz bag liner
- 6.8 oz bivy
(total ditched) 32.8 oz
+ 0.6 oz / Klear water (repackaged in dropper bottle)
+ 0.3 oz / plastic cup
+ 0.4 oz / mosquito head-net
(total added) = 1.3 oz