RE: nutrient sachets
If you read Stanley Burrough's original text on this cleanse, you'll find it's pretty convincing to go sans supplements--the lemons and maple syrup are rich and the body is designed to find equilibrium. I don't think the Amazons were taking supplements...
I vote that you try to experience letting your body find its natural center. Hopefully you can find enough proof that noone who has completed the cleanse was in danger so that you can with peace of mind try to let go of all aids etc.
I find that the hardest part of fasting is mental, giving up all the cultural and psychological ties I have to food. Being on the fast gives many people an opportunity to meditate on this relationship and come through with fewer addictions (I no longer drink, smoke or eat processed sugar--the last one only with SUPREME effort, and I have to keep re-dedicating myself.) I've had to journey through many inner peaks and valleys to break myself of these habits. I'm glad I did.
None of this is to say that supplements are a bad thing--I for one wonder if they are really necessary?? I have alot to learn there.
Good luck what ever you choose!!