I fill empty vinegar bottles and freeze. A full freezer keeps temp better than half empty. When I process birds I put in the cooler for ice and swap every 8 hrs. And If I need room in the freezer , its easy to take them out.When we're expecting a hurricane or tropical storm I fill up the freezer with bottled water, laid on their sides. I've never had one rupture.
If the power goes out the frozen water helps to keep the freezer cold. And in a pinch we can drink the water.