How many pounds of fish? Ice always helps, but be VERY sure to acclimate and temper the fish at home with your pond water. Frozen Ice jugs are a good idea, but once melted, pour the water empty the jugs into the cooler, for the fresh water (make sure it's chlorine/chloramine free water), because ammonia build up is a bigger danger to fish than the water temps are.
Using coolers, I'd travel in the daylight when places are open, should anything go wrong.
