I have a Coleman 12V cooler which I absolutely love. The cooler keeps things very nice with no ice and can be stood up to work like a refrigerator.
A while back I installed a 12V outlet in the bed of my truck. While traveling I plug the cooler in and it keeps things cool for my arrival. The plug is switched so only operates when the engine is running.
While camping I had replaced my 12V converter, which I purchased just for this, with a simple outlet installed in the battery compartment.
I simply unlock the compartment, plug in my cooler then shut the door. There's AMPLE space as to not damage the power cord and the converter powers the cooler with ease. No more separate 12V power supply and I have an easily accessible cooler / fridge.