If you plan to maintain your Illinois residency, you would simply keep your house in Illinois as your main home, and not register to vote in GA or register you ca and get a new driver's license in GA.
You will likely have state tax withheld for working in GA and will file a nonresident state return there. You will file a resident return in IL and will take a credit there for tax paid in GA. You can no longer take living expenses in GA as a job-related expense, so it does not matter if the job lasts less or more than a year.
