In terms of hydration, Saturday's ride had me consume 3 bottles of water and 1 bottle of Perpeteum (5 scoops). Unfortunately, I didn't weigh myself before and after to see how badly I was depleted. ☹
For calorie intake, I had the Perpeteum (about 600 calories), and 3 servings of HammerGel (about 300 calories) for a total of roughly 900 calories. According to my HRM, I burned off 1900 calories. Post-workout was a bottle of Recoverite at about 120 calories.
Looking at it that way, I guess I was short close to 900 calories for that day. And I do recall noticing my sweat rate dropping significantly after 1hr45 or so.
I think next time I'll have to increase the water intake during, and make sure I get more than 120 calories after the ride. And I really, really need to start weighing myself around these longer sets.