Don't worry too much about the costume thing unless it is really something that interests you. Just read the rulebook and comply.
Kayne Robertson, Past President of the NRA, shot with us this year in a campaign hat, dark shirt and Wranglers. Don't remember what kind of boots. I just wore my cowboy hat, Wranglers, long sleeve shirt and Redwing work boots with smooth soles. I kinda hate these discussions as they always sound like I should add "with matching shoulder bag and gloves". Do remember that some do like to dress in clothes of the period, military of the period, or just wear the minimum to shoot all of which is good. Many CAS shooters just wear their CAS clothes. I know shooters from rural areas that wear their everyday working clothes. Important fact here is Wild Bunch first and foremost is a shooting contest with a real power factor, smaller further out targets, as well as some close burn down stages, and lots of mag changes. Many matches will be adding military boltgun, speed matches and other side matches including shotgun to add to the appeal. We are working on the definition of a Senor Category and will have it worked out soon. Pretty sure it will be 65 and above and Traditional and Modern classes will have to have enough for a class before the Senior is activated. Still discussing the minimum for a class now. At EOT, the World Championships, we had World Champions in Long Range Bolt gun, speed rifle, pistol and shotgun as well as wobble trap team. Come and shoot with us. We have lots of fun.