In my previous life (pre motorcycle instructor and driver examiner) I was a dispensing optician, for 32+ years.
The problem with sticking polarising film over the clock faces is that 1) you have to orientate it correctly so that the polarisation axis is in alignment with the glare you are trying to eliminate and b) you may find it harder to read the clocks under low illumination.
The idea about wearing a pair of polarised sunglasses is a good one, because then you control when you have the reflected glare reduction in place, and of course you won't be wearing them under low illumination. I swear by (not at!) polarised sun lenses.
The only down-side of the whole polarisation thing is that it the filters show the stress 'contours' in heat tempered glass, such as the rear windshields of cars, and it can interefere with the clarity of digital instrumetation.
I'll try to help with any other optical related questions out there....