Ive only seen large female toads grow to 3-5 inches which makes sense as the females are larger than males .Hudson Bay toads (anaxyrus americanus copei) are a subspecies of American toad that can be found in the northern parts of several provinces in Canada. They are not usually found in my area as I don't live way up north but there have been reports of toads not too far from where I live with their distinct patterns. It is very likely that as you stated that the toad that I witnessed was just a specific colour morph of eastern American toad for the area I was in as I have notice that different areas of my region have eastern American toads with different distinct patterns from toads of another area. I can post pictures if I see anymore with interesting patterns .