I'm not sure if this could change much.
I mean even without any pole wpf a lance is not that bad to control on horse. The only thing would be the upkeep, but with about 6 WM your main weapon (pole, 2h, 1h) plus some points in lances it would be totally possible.
Not sure if it even was possible though. I could like this, not only because of 1 slot, playing both lancer and 1h at the same time though lances should of course stay unsheathable.