Only thing I'd change is dump the jacket and ranger blanket for a softshell jacket.
The ranger blanket doesn't do shit if there's more than a 2km/h wind anyway, and a jacket takes up too much room.
Goretex is for garrison only. That whole "goretex breathes" thing is complete bullshit. It doesn't breathe enough to stop you from fogging up when you're NOT running around.
Softshell fabrics are 60-80% waterproof, lets just enough rain in to keep your core temp down, keeps enough rain and wind off to prevent you from getting cold. Plus doesn't make that goretex crinkly noise lol
Using a chest rig, I'd say bring a thermal shirt just in case you need it under your softshell.
Advantage to plate carriers is they also keep your fairly well insulated. Between my PC and soft shell I'm good between 10-20 degrees, in rain, and high winds.
Food isn't as critical as you might think. I've done 24hr ops with 4 stripped IMP's and I've done 24hr ops with just vector bars and beef jerky, and I've got a pretty high metabolism. For only 12 hours I don't think I'd even bring an IMP.
Water is critical though. I'll usually add NoXplode to mine as a vasodilator, energy supplement, taste, and faster absorption.