I would always approach the drivers window and direct the driver to exit the vehicle with his DL and registration. All conversations then occur outside the vehicle on the passenger's side. I never had an issue with any RVr that wasn't polite and accommodating. Then again, I was always respectful of them too. Respect begets respect. Now if the freeway was really busy, I might approach the front passenger window and give directions to exit the vehicle there. Either way, rarely will you see a LEO writing a ticket etc. while the trucker/RVr etc sits inside the vehicle....as I always told my kids, there's 78,000 violations in the California Vehicle Code, just sitting in your car, you're probably violating several. Be a jerk and the officer will find those violations. How you handle yourself goes a long way to how long you are going to sit there.
I'm reminded of the traffic stop I made where the guy was a real pistol. He kept yelling and using profanity while I was writing his ticket. I was on my third ticket before he asked what I was doing. I politely told him as long as he kept talking, I'd keep writing. He shut up...:B...Dennis