I thik your plan is fine except for a few things. You can flush with ES before you start your fast, but not after the fast. I usually flush my body with Vitamin C. Second, you should not do any enemas during your fast. It does not make sense to use your body energy for something else rather than healing and cleaning.
You eating plan should not have to start with vitmains and electrolyte sport pills. You really wan to slowly build your appetite with fuit juices and vegetable juices. No oils either. Everyting in plant based foods will be good enough for your body and it will suck all nutrients out of those foods. Salads can be eaten lemo or lime juice freshly squeezed on top. Also avoid spices including salt.
Length of your fast depends if you will be working or not. It is always best to rest and stay warm during fasts. Walking is ok.
Also do deep breathing for back pain. Everyday sit in one place and do deep abdominal breating. That helps with all pains and aches.