Thanks for the great info. In terms of flying as an ultralight, my understanding is that any aeroplane - regardless of the category it is registered under - that meets the definition of an ultralight airplane (ie 1232lbs gross, 45mph stall...) can be flown by an ultralight pilot. But that same plane...

I've been searching for a while to get to the bottom of this. How does the process work for having a different gross weight for wheels vs floats? Would this be handled in the POH (or Aircraft flight manual)? Would the aircraft have multiple special certificates of airworthiness (one for wheels 1232l...