I'd suggest renting the Trawick Pavilion and making the event a trailing tournament. That way you have a nice shaded area with picnic tables, volleyball, and basketball too. The lake fishes good year round so the bite wont be an issue. MAKE SURE you acquire the proper permits, there is much more to it than just renting the Pavilion. You must get a permit from the city of Grapevine for the event, they may require health department certification if you are serving food, and may also require you to insure the event. This is why most of the bigger tournaments out there run the events offsite from the actual parks and allow anglers to trailer. Its not as simple as it once was to run an event on the Vine.