It looks as though the Goodyear cargo could be a possibility. I will look into those and see where they are available. Keep your opinions coming on this tire choice please. Especially if you have real world experience with them.
One note, I am trying to stay with 15" wheels because I have two spares I carry on my long trips. I am trying to avoid buying 6 tires and wheels so that is why I am "pushing" a little harder for a 15" tire choice.
Yes, optional 16" wheels/tires was an option on my trailer when I ordered it. Being new to large trailers I did not know the importance of this when I was making up my options list. Today, I would take that option without even thinking about it. Back then, I thought it was more of a cosmetic thing than a matter of function. Live and learn.