As I recall, Chatsworth House undertook major repairs and they used decent images pre-scaffolding, which when combined carefully in Photoshop, with pictures taken 'on the day' complete with scaffolding, allowed an attractive images without the scaffolding in the picture at all.
Perhaps the organisers/photographer could do some pre-event pictures to achieve something similar?
Anthony.
http://www.bbc.co.uk/programmes/b01jjy9d
"Episode 3
Duration: 1 hour
Summer arrives, bringing with it wedding season at Chatsworth, but there is a veil hanging over proceedings and it does not belong to the bride. For the entire 2011 season, the famous south and west wings have been covered in scaffolding as part of a massive renovation; but it could spell disaster for their burgeoning wedding business and the all-important wedding photographs. However, ever-resourceful events manager Kay Rotchford has some Photoshop magic up her sleeve...."