Keeping rain off your MH mirrors

StuartO

My mirrors pick up rain and spray and they are not heated, so they become difficult to see through, especially when there is heavy rain.

Has anyone come across a way of keeping them clear or clearling them, for example by attaching an air scoop to the housing in order to blow air across the mirror surface, or a shied to keep the stuff in the first place.

My motorhome by the way is a 2006 Hymer B674, so the mirrors are rectangular and adjustable, inside black plastic housings.