I'm finally doing it for one hour in 95 F heat. I used 1 slice of wheat bread with salted butter and brown sugar sprinkled on top as fuel. And then ice cold water with a pinch of salt for hydration and additional source of electrolytes.
Worked wonderfully well. No upset stomach and felt adequately fueled and hydrated throughout
I guess that means no more orange juice for me, just very slightly salty water and sweetened salted butter sandwich.