Bob, looks like you are off to a very rapid start. I didn't know if you used treated lumbar for your sill plate or put a moisture barrier on it. Whatever dimensions you decided on, double them for future plans.
My collection has grown more rapidly than my storage will allow, so I am entertaining the idea of putting up an 18' x 21' steel storage building to catch the overflow.
Keep up the good work and keep posting those pics!
Cub Cadet 123