cooler and an areator? 

Buy a cheap aquarium aerator pump, stone and hose from wally world, get a power inverter and run it from that. Drill a hole through the lid a cheap cooler that doesn't have a drain plug.
You can keep live bait live, but also when you catch a limit of crabs and don't want to eat until the next day, take home and plug into the wall outlet. You get about 24-30 hours before they begin to fade without changing the water.