Here is what the Yetis site says about dry ice:
Use one 10 inch/10 pound block of Dry Ice per 15 inch length section of your YETI cooler. This will ensure everything is kept frozen, including water ice, for at least 24-48 hours.
Wrap each block of dry ice in several sheets of newspaper before packing.
Dry Ice can be packed on top of or below food, but it will keep longer if packed on top (for convenience, many people pack it on bottom).
When packing the cooler with dry ice, try to minimize air pockets (empty space) in your YETI. Less air space will keep dry ice frozen longer. Water ice can be used to fill this space.
As with regular ice, try to keep your YETI in the coolest temperature spot available. Covering your cooler with a blanket or sleeping bag will help preserve all ice longer.
Dry ice can be used in combination with cubed or blocked water ice.
Nothing about a cooler insert to hold the dry ice. Just the newspaper wrap technique.
But here (How to Store Dry Ice: 5 Steps (with Pictures) - wikiHow
) I found:
Prepare your container. Dry ice should be stored in an insulated container; the better the insulation, the slower your dry ice will sublimate. A polystyrene cooler will work well. A small polystyrene cooler inside of a larger 1 will work wonderfully - the air space in between the 2 coolers provides added insulation.
Your container should have a lid, but it must be a loose fitting lid. Storing dry ice in an airtight container presents a huge hazard - the carbon dioxide gas will build up and eventually produce enough pressure to cause the container to explode.
MAKE SURE BOTH COOLERS HAVE A LOOSE FITTING LID.
Or you vent them on a schedule.