I envision a day where I could have a baumkuchen oven in the back of, say, a Chevy Astro.
You know, like an ice cream truck, except selling cake instead of drugs.
Bakeries/pastry shops seem like they would be pretty easy to make portable; one could use a similar vehicle setup for regular cakes, hotcakes, cookies, breads, &c. These would probably be better suited for a confined space like a van because the ovens can be smaller, but I still think this would be the best way to introduce baumkuchen to the most people.
There's not much content I can add right now. Craigslist has offered up a few potential parts sources that I will check out this weekend.