Why not an area, probably green fields, for the competition houses?Like my suggestion of making a special area for people to have their deco houses in
You sign up, you get an 18x18 or joined 18x18 allotted (0 slot of course) and a house-house teleporter to place in one of your regular houses.
World teleporter access so people can go view. (Possibly limited to between the entries closing and the place being cleared)
Then when it's time for clear down, it can be done automatically with gold from customization going back to the entrant, and any items going to a moving box in the designated house. (ie: where the H-H teleporter was)