What did you do and use to clean off the bird bombs?
How quickly did you get to the top after it got bombed?
Was the vehicle out in the sun all day when it happened?
I have personally used RaggTop products, their Cleaner and Conditioner spray very successfully in my Shop in the Pacific Northwest, which for some reason has a huge amount of Convertible cars for the amount of rain and snow up there every year..
Dan F