As I said before the GF juice is for flavoring only. The original recipe calls for water. I am sure any juice you find that is palatable to you will work or bite the bullet and do it with water. There is nothing to "psyche" yourself about. It's a pretty benign process and very very rarely are there any complications. Just relax or you will psych yourself into an unecesary bad experience. You'll be just fine. Just remember not to eat any fats the day of the flush and don't eat anythig after 2 PM but do keep drinking water as the E Salts are very dehydrating.
The tongue thing was what it was this time and the next time it will be different like it was different the last time. Like I always tell folks "que sera sera" Don't make a big deal out of any of it. There is nothing to figure out. The fasting part is the "easy" part. The "no brainer". Where everything was all figured out for you. The "true" benefits are yet to come in what you put back in and all the daily decisions you'll hafta make after taking the trash out.
The Cucado soup rocks. Make sure you peel the cukes and seed them and it will have a wonderful smooth refreshing feel good taste/texture. For another super raw soup treat, if you have a way to make carrot juice put some juice in the blender with an avocado and add 1/4 to 1/2 tsp of powdered fennel. Magnifique!!