OK, well the reason that the polariser is put at the front is that what it does is stop polarised light, it doesn't make the light polarised. That's why you rotate it to control the amount of polarised light getting through and either on to the lens and hence sensor, or on to any further filters which you might use.
Now the resin that Lee use is very closely controlled and should not have any distortion or stress effects, hence my comment that you can put resin filters in front of a polarising filter although it really is not recommended and in a situation with bright light and reflections any resin imperfections would (or could) show up.
Polyester on the other hand is much more likely to have stress imperfections and polyester itself is inherently a depolarizer, so putting the pol filter after the poly filter is much more likely to show up imperfections in the poly filter, although again I have to say that it is not necessarily the case, it depends on poly quality, light conditions etc.
The conclusion I am trying to get to is that whereas you may get away with using the polariser as the last filter before the lens, because of the above if you put it in front of any other filters and is therefore the first filter the light sees on it's way to the sensor, that will always give the best possible results.
I hope that helps!!
George.