A short update on this matter, just in case someone is interested.
We still didn't come up with a workable solution and I guess we never will. Selling the kind of cookies I do professionally just seems impossible.
BUT, I'll be teaching my first classes soon 
Well, to be honest, co-teaching. I have been asked by my teacher (where I take the PME professional courses) if I'd like to do a class together with her. She has a fully equipped studio and a reputation in the cake decorating scene in Germany - and told me that I have to start with something, why not by giving a beginners cookie decorating class with her?
She has been thinking about this for quite a while, but always refrained from stepping further for the following reasons.
- a class needs at least 6 people to be profitable
- 6 beginners can hardly be handled by one person
- 6 people with advanced or at least intermediate skills in cookie decorating who are also willing to take a class, are the needle in the haystack around here
- she couldn't find a co-teacher so far for a beginners class
Ha, and that is where I step in. I'm so excited! My mission to spread the cookie virus in my part of the world will finally beginn!!!