I have a Citabria and we've flown with the door off a number of times for photo work. I've never heard of having to have an STC to take the door off. It certainly doesn't change the flight characteristics to any noticable extent. But I'm sure if you look hard enough you'll find a governing party that will make you sorry you asked.
That's my problem. I will do some stunt flying for a moovie and we need a lot of other approvals to do that, consequently I need one also for this part - so if anybody know a formal/legal way to fly without the door, please.
I have an 7EC that has legal paper work to have the door off in flight for photo's .You may be able to adapt it to your plane. Same door opening?If you need a copy.
I recently completed a 337 for an STC to fly with the door off of a customer's 7ECA. It involves a placard about "no aerobatics" "no smoking" and a never exceed speed while flying sans door. This is definitely required paperwork for doing it legally. If you're interested I can pull the file and get the STC holder's info.