Here's what Mass Ayoob thinks (video)
http://backwoodshome.com/blogs/MassadAyoob/2017/07/05/when-pulled-over-while-carrying/
http://backwoodshome.com/blogs/MassadAyoob/2017/07/05/when-pulled-over-while-carrying/
The officer should tell you why you were pulled over, and usually they like you to keep your hands on top of the steering wheel.That works for me, combined with a "What'd I do?" and both hands on the window sill.