For some, extra security is a must. One method is to start with a very sturdy, lock-able structure and clad the exterior with period details. This is also good if you are able to keep this structure on-site when the Faire is not running. The base box is weatherproof; include a watertight roof membrane, pad lock door, and interior locking shutters. In the second image you see this same box with its themeing applied to it. These can remain year round, or be stored inside between Faires. A peak is added to the flat room and boards are placed around the base to hide the concrete supports. The old Northern California site frequently flooded during the winter months, so concrete piling were a must, but your site might not need such details. Also check with regional building codes to make sure you are not violating any rules, or making sure it is understood that your structure is a non-permanent shed. Each area will be different so it pays to double check.