tarheal63--I very much appreciate your advice and the links. I kinda figured that longer arms would translate to being a bit more stable--I appreciate the reinforcement! I assembled my frame this evening. I think my arms are about 20" so the diameter will be near 3' or so. When it's done I'll post a pic or two.
Well we're getting a bit of snow tonite and tomorrow--it will be a good day to work on this build!