Interesting information about the sweet potatoes. They always work so much better for me than regular potatoes. Of course, I am a Type one, so have no automatic insulin response at all.
I had a thought about your comparison meals … how did the fat content compare? You did not indicate how much fat was in the smaller meal, but the fat level in the large meal was really high. The high fat content could have delayed the “spike” in that meal, which looks like a good way for you to avoid the spike altogether (looks like your body is able to compensate for the spike later, but not right away.) If the fat content in the small meal was significantly less (proportionally), that could explain the 1 hr spike.