We are towing the same vehicle, (2008 convertible).
Key needs to be in ignition but does not need to be turned on. We turn the key on and make sure steering is unlocked, then turn the key off and do not remove it. So far, it works for our entire drive.
NOTE: We are new to towing the car and have not gone more than 75 miles away yet. It has not locked during travel but it is one of my concerns until I really get a chance to test it on an all day drive.
Norm & Ellen Proud to be one of the HOOTS
2015 Newmar DutchStar 4369
If I knew retirement was so much fun, I would have done it in my twenties!