Soldier seeks survival

I am deployed to Afghanistan and have a weird schedule. I work on an Afghan compound and have to sleep out there for three days at a time then three days on the US side. When I’m out there I don’t have access to a gym, and I’ve been trying to make due with a full ammo can and a 240B machine gun. I need to stay in shape, keep up my strength and endurance and sanity. I have access to supplements via mail and protein powder a' plenty. I could really use some help coming up with a workout that will allow me to maintain and improve my strength and endurance. I also don’t have access to cardio when I’m on the compound. I could use a point in the right direction.