One option you have is not do a visa run. When it is time to leave from EZE in January, go to the airport an hour earlier and pay the overstay fee. That means you will not go to any other country until you leave Argentina. If you go to Colonia (or any other country) before your visa expires, I don't see why there would be a problem. I never heard of any problems and people are doing it forever. Just have a nice attitude, the custom officers are very nice people in general. Also, if your wife is with you, she will make sure no one messes with you
But seriously this means you have to make the run twice before leaving in January, so consider staying over and pay the fee. It is much cheaper that way.