The OP may have already thought about all this, but there is definitely more to designing a good fun fly plane (or any purpose built plane) than choosing the right airfoil. You need a tougher than usual landing gear setup, preferably with some shock absorption, big control surfaces for maneuverability, and the lightest possible weight. The venerable old Ugly Stick with a stronger undercarriage and flaps added has been a constant contender because it's pretty close to ideal, but as these kinds of events have continued year after year improved designs have surpassed it.