Children reacting to the songs you have put together could be fun. I don't know where you live or how the outdoors effects the musical equipment, but i am sure your local government parks association would be fine with you holding the occasional free concert in their local parks. But getting approved to film it as well, might be another story. Regarding costume change: I honestly have no idea what you would be looking for, and comfortable in. Maybe something more whimsical? 😆 I am not certain a green pointed felt hat would work as well in this day and age.