So, to conclude. I haven't been for a drive at night yet to see how it all works, but using 2/3 coverage will seem to work for me, with my position in the car. I will probably only put the film on during night driving and then take it off the rest of the time, it is easy to put on and take off, with some special static film strips that come in the pack, or you can make it just a bit too big in diameter and it will slip under the chrome ring and be held in place.
So I can't completely reccomend the solution, it is not optimal, and is probably also reliant on your own position in the car. But, now you have something to think about :-)