If the stop sign is on private property you can't be written a citation for running it, but in this case the sign is most likely on public property controlling traffic access to a public roadway. Your best bet is to go to court, meet with the prosecutor, and see about getting the charge reduced to a non-reporting violation such as O.C.G.A. 40-6-180 Too Fast for Conditions.
James L. Yeargan, Jr. is licensed to practice law in the State of Georgia. All information given is based only on Georgia law, and is not directly applicable to any other jurisdictions, states, or districts. Any answer given assumes the person who asked the question holds a Georgia Drivers License, and this license is not a commercial drivers license (CDL). This response, or any response, is not legal advice. This response, or any response, does not create an attorney/client relationship. The response is in the form of legal education and is intended to provide general information. Any state specific concerns should be directed to an attorney who is licensed to practice law in that respective state.
I agree with Mr Yeargan, but let me add that you could also hire a lawyer to do the same thing for you. That would likely increase your total cost, but it should also increase your chance of success. A lawyer who practices regulalry in the court you are going to and who has a good reputation will greatly improve your odds, in my experience and opinion.