Hi,
I had look at your plans but i found it hard to understand as it is difficult view it with excel. But i made a very simplistic version so you can play around with it yourself to get the final product that you need.
Pier.skp
I'm sure there's is someone beavering away on it at the moment and will upload a better version soon enough. But to help out a little hope you view this and play around with it
rgds,
Rich