Let me go back a bit to your last question.
Wouldn't there be too much sugar in the chocolate skim milk and the banana to be considered a healthy supplement according to SBD?
Bananas are already a P2 food and skim milk is fine in all phases, so really the only thing that would add more sugar is the chocolate syrup added to the skim milk. I don't know if it is still in the Supercharged book or not, but Dr. A in his very brief discussion on exercise talked a bit about recovery foods and basically your body does best with higher GI carbs and protein. In the original book he even talked about white bread as a recovery food because it is so much higher GI and white bread isn't really part of SB either! So it is more about specific foods for specific purposes.
And I don't really know the answer to your question about a 3 mile run. I'm neither a runner nor an endurance athlete. Based on what oldpjams has written here in the past, I tend to think of it more in terms of time spent and when you get into the range of 90 minutes or more then you really need to be doing something more in terms of both fueling and recovering. Since a normal walking pace is 3 miles an hour, you should be under 60 minutes with a faster than walking/running pace, so I'm not sure that would qualify, but really it's a question better answered by someone who runs as I just don't know.
I think the drink you outlined is within P2 guidelines as is, so don't really see an issue with it.