don't dehydrate juice. try the 80/20 option.
1. you can boil it down to a thick concentrated syrup paste. reduce water by 80%.
2. you can add thickener like flour, sugar, salt, cocoa, cinnamon to harden it and speed it up.
3. spread the thick paste into a thin layer on a wide cheese cloth in a dry area, or if you have a smoker to get rid of that last 20% moisture. Until you can get it bone dry into a solid powder
4. or wrap the bulk of the paste in a cheese cloth, tie it in a ball bundle, then put something heavy like a brick to slowly put pressure and squeeze the water out. the cheese cloth acting like a filter. capture the squeezed out water, its drinkable, dont waste it.
Shelf life without preservatives (high sugars, high salts) is still very short.
instead of powder being the goal, you can aim for concentrated syrup, but that will need heavy sugars, that may be counter the "healthy" purpose. I suppose you can use honey for sugar instead of the white powder smuggled from the island of San Glucose.