Well I've finally started giving these some thoughts and alot of my 'road blocks' seem to have melted away by the application of KISS and the 'startling discovery' of a new specialist deck 'Siege-Fare' (I'm surprised you all couldn't hear the sound of palm on forehead) and the 'realisation' that all that needs to be played on the board is 'the final assault', all the rest can be covered by board set up. The downside for this is designing the specialist cards......
My last big issue is the board and fort creation. I'm leading toward two maybe three castles and having them as scenarios though I'd love to have that flash moment and sort out a 'balanced castle design' setup too.
Chris