First of all, I propose not to use collision mesh, but some procedure to define where windshield wiper is. (You will save a lot of performance with that). Just make some attribute for effect, that defines wiper angle, size, etc.
Then you will be able to control with the same attributes geometry in engine and data in effect. Also with attributes like wiper length, etc. you will be able to make customization of effect for different car models.
Then you can kill (or, what I prefer, change LifeRatio to point, where particle starts changing transparency to 0.0, but only if it’s fast enough) raindrop particles based on theirs position if it intersects with wiper. Also as you have actual wiper position, angle and size, then you will be able to spawn some particles to imitate water accumulation, on the side of wiper movement direction.
Also good to have some ribbons on back side to imitate thin layer of water that dries out.
That’s just my 5 cents. Good luck with the effect.