Fresh water. Shelter. Dogs.
Since you've good weapons/ammo and food listed.
You die faster with no fresh water than you do with no food.
You have to sleep, safety in your sleep is accomplished with shelter and dogs. At minimum dogs make enough noise to wake you. If trained right, help you hunt, and guard (at least watch, if too small for guard) while being great companions.
I was thinking iodine or water purification tablets in my top 3. You are correct about not living long without water
(post is archived)