Other items of consideration:
Mess kit
Non-perishable snacks (protein bars, dehydrated fruits, jerky etc.)
Camel Pack
Plenty of spare lights (Headlamps, ballcap lights, camp lights etc)
First aid kit (An IFAK if you have it, probably over-preparation)
I have body armor, I'm going to bring it. Almost certainly over-preparation, but I figure I have and if I don't wear it to this what did I pay all that money for? If you already have it it'll only cost you the not-inconsequential extra weight of carrying it. but on the same note; shinguards, kneepads, jockstrap & cup, all of that is 99% over precaution but I just don't see how It could hurt to bring, especially if we're on shield duty.