My favorite addition on my last long trip was a camel back water bag. Mine is 1.5L. The lower half of my tank bag is insulated so by filling up with ice then topping off with water , I was ensured a cool supply of water even on the hottest day. I didn't realize how much I wasn't drinking until I got this system. Highly recommend one.
I pack protein bars but really don't rely on them. When riding long days I Really try to watch what I eat. A few boiled eggs, a string cheese, banana , yogurt are some things to mix and match that provide quality low fat calories so I don't get fatigued. These are things that most fuel stops have now days.
Sunscreen and some sort of block for my neck as the sun can take a lot out of you. I Recently cut 10" from the waist of a t-shirt (Cammo), double it up and wrap it around my neck; it blocks all the sun and that helps a bunch.
Don't be Married to a stop time. If I remain flexible I find I have less fatigue thinking about it. When i have a few hundred miles to go and I'm tired I take long break, so it means I get to where I'm headed a little later, I feel refreshed after closing my eyes for 15 minutes waiting for my dinner.
Hope these tips help on the longer days
