I Agree with Paul and Karri - 101%
Please do let us know the "complex" business requirement to do this... maybe, there is an easier alternate! Maybe Program exits can help you to track only the 'required' workitems and not ALL! Maybe we are over engineering! Look at the future - people maintaining this 'Z' development will always be pulling off their hair!
But then, Maybe, there is some requirement which we cannot think of and which lead you to this design!
Regards,
Modak