I am playing the Sgt that taught me to play in Okinawa in the 80s and in no way would Marines at the very least, be missing all of their basic supply items issued to EVERYONE. Only if they were somehow captured first.
After some 3 years of war and probably a couple of years of almost no proper CSS, I can see how a lot of these things could have been broken or lost. I agree that things like rain/cold weather gear are vital enough to make sure they're present and usable. Same with e-tool and gas mask, though I can see the mask being damaged during the 3 years or the filter being saturated or waterlogged. However lugging 2 extra sets of fatigues instead of extra food/water/ammo seems really odd to me. Small stuff light flashlights can be lost or broken. The most common case I recall is when you camp and pack up in dark, sometimes something just falls out of your pouch and you don't see it. Yes, in an ideal world it wouldn't happen, but in real life it does. Similarly you might be unpacked, having a food break or something and there's an enemy contact. You will most likely leave your canteen or backpack instead of risking with your life. Add all these complications and no support/low supply stocks and multiply it by three years of war and you don't have all those "fresh out of the warehouse" kits anymore.
Not saying you can't do it for your game, just that the way the world of T2K is presented, I doubt anyone would have all of their issued kit anymore.