Whoa. I have also been vegan for a few years. You might want to look into creatine (which boosts intelligence, especially in vegans) and IF/CR if you haven't already.
Have you ever tried recording what you eat to see how the nutrients add up? I might try something like what you're describing in a few years.
While for a couple periods I counted my calories, measuring nutrients--either of the food or my own--is a low priority for me. If I could afford to pay someone to do these things for me I wouldn't hesitate. I'm content for now with this simple reasoning: How bad could it be to eat only fruits and vegetables? Plus, I can alter the diet in a moment if needed.
For the past few years my willpower has been steadily increasing. If it lasts and I use it to accomplish something noteworthy, I might write a post about it.
Anyway, what should a rational preference utilitarian with infinite willpower do? Assume that there are no negative effects (unhappiness, stress) with using this willpower, and that they can control their emotions at will.
Clearly they should work a lot more, not spend time on recreation (movies, TV, games), stand instead of sitting, etc..
What else? Should they listen to music? Should they keep their muscles flexed 24/7 ? What should they learn, where would they have the most relative advantage? How much time would be worth spending on social interaction?
I can figure out these things on my own, but those questions are important and good ideas are very valuable.