My APC tactic is to just bail it (so it's empty on the map), but hide under the tracks to shoot people. Only works with the American/British APCs, but at least you can be outside the Purple Heart Box when you earn one
. Really works quite well, if people think you're near the APC at all they think you're behind it, and the tracks work well at deflecting bullets. You're quite boned if someone riflenades you though.