My freezer is filled with food BUT I lined the inside with 2 liter soda bottles which are now ice. They will help keep the food frozen for a little while and when they melt I have water. They do take up space in the freezer but I don’t typically freeze a lot of stuff.
We do the same thing, especially in summer. I can now stand anything a mid-summer power outage brings, EXCEPT not having cold water.
-JT