If you are in a cold area I usually add water to the cooler that is 5-10 degrees warmer then the tank water for about 15 to 20 minutes to help keep the water from cooling down to fast
What i like to do is use buckets or rubbermaid totes...you can put them in trash bags and tie up so when they splash it wont get any in the car.......also drill a small hole up top for a portible air stone
Thanks for the advice everyone! I think I'll use some cheap totes wrapped in trash bags. I don't have to go very far so hopefully I can skip the air stone this time.