I have just put on a Ultimate seat. I knew from research it is not water proof. They did send a seat cover for it (frog togg material) and say it is for riding in the rain as well as sitting in the rain. I went to wash my bike yesterday and debated on how much water I could get on the seat. When pulling it back into the Garage my back side wasnt wet so I guess I did ok.

Not the same as your situation but you would think a rain cover would have come with your seat for that much money and the fact it isnt waterproof.