I did some research today and found a plug in fuse/switch at RV-parts.com ($39.95 US). Company is sending me some photos of an installation on a 2010 Malibu. By removing the fuse it will eliminate battery drain but I am not sure if miles will accumulate on the odometer. I previously towed a 2003 Saturn L200 and removing the ignition fuse kept towed miles of the odometer.