Pony Poo - aka Horse Apples. I've never tried to use them as a deliberate source for fuel, but when dried, they do burn quite well. They are not similar to cow dung at all in consistency and instead pretty much start out in "cubed up" form. Even when dried, they are fairly easy to break up - actually pretty fragile in that regard, wet or dry. Compressing it might add some structural strength to it - I'd be interested to see your results.
Chris, I have a question about your reason for going this route - why do you believe that the neighbor's fence would go up in smoke if you put the exhaust for an RMH there? A properly setup RMH should have an exhaust temp that could lead to drying, but not incineration. At least that is what all my research has led me to believe - especially with the videos that show folks putting their faces into the exhaust without ill effect.
Here's the one I'm thinking about: