And the answer is...
...I have no damn clue.
Atticus, you hit the nail on the head when you said that there has not yet been a test case. To me, "in plain view on your person" would mean that it would not be concealed by your clothing or any other holster/bag/etc, but the seat or seatbelt or other interior car parts might obstruct the view of it, depending on the angle of the viewer. However, I am also not very likely to be going out of my way to hem up a CCW holder. YMMV, depending upon who you get on the traffic stop. I can also understand (but not be happy about) an interp of "in plain view" being more strict than that.
One way to help deal with this might be to carry it thus, but if pulled over immediately unbuckle your seat belt, turn so that is is even more visible, and put your hands on the steering wheel. When the cop walks up the first thing you should say is "I have a CCW permit and the gun is on my right hip." That way he can look, see the gun, and decide how to proceed.
Could you still end up being a test case? Yeah. You sure could. I'm not particularly happy about this provision, either. Its dumb.
Also, the idea of a paddle holster that gets tucked into your waist up front has real merit. #1, it is hard to argue that this is not in very plain view. #2 drawing from it (which is always hard using strongside IWB in the car) should be a snap.
Be warned: I don't think that carrying it in a holster laying on the seat beside you will work. I don't have the text of the law on hand, but IIRC it needs to be in plain view on your person, or locked up. Not in a holster laying beside you.
Silly law.
Mike