A car battery with an inverter is prob the best way to power equipment (other than a generator). You can buy a power box with the inverter built in, and run an air pump as your "stirrer" for days. Otherwise a battery powered airpump with a supply of battery is next best .... or stay up all night stirring the tank manually.
Of course it is too late to go get stuff now the storm is going to hit within a day .... If your car battery is fully charged, and you are handy, you can borrow your car battery for the tanks. <Or run an extension to your car power outlet with an inverter.> But make sure you have a charger to charge the battery back up after so you can start the car .... and make sure you don't need to use your car to evacuate, etc before you do this.
Doing a pwc before the water goes is good idea. Also, save up extra water for emergencies (you & the tanks ....).