Goal: Create a hanging bag to safely store items in your car from common household objects.

Which of the following methods is more reasonable for accomplishing this goal?
Create a hanging bag to safely store items in your car with common household items by attaching a carabiner to the handles of a fabric market bag. Attach the carabiner to the metal posts of a cars head rest. This will prevent items placed in the fabric bag from rolling around or becoming projectiles during a car crash.