Is is possible to minimize the amount of salt spray on your windscreen by just keeping a greater than normal distance from the vehicle in front.
My Mrs came home the other day with the front of her car covered in salt. You couldn't even read the front number plate. I have done the same journey 3 times since, and got hardly any spray on the front of mine, and I'm convinced this is down to the way we drive. I will keep a good distance behind the vehicle in front to keep out of their spray, and if there is a car overtaking me, I will ease back a bit further so that they are further away from me when they pull back into my lane. Also when overtaking lorrys, I hang back until the road is clear enough for me to accelerate past quickly so as not to be boxed in beside them for too long.
There are times when getting sprayed is unavoidable, but if you treat the spray as another vehicle on the road and give it some space, you should keep your screen cleaner for longer.