As my pictures on webshots will show you, I attempted the Croom 35 alone one hot summer day last year. I was carrying plenty of water, supplements, and even two extra bottles. It didn't matter I had the extra water, the heat got me by 11am. Almost passed out of heat exaustion. Not a good thing... specially alone... Dumb, dumb...
I have reached that point where you take one zip of water and your water kamel bag just kind of gargles back at you. The sign of "oh oh" I am out of water and need another hour to make it back. Not a good thing. If you need extra water, you have no choice but to ask someone for some. I carry two botte cages on my bike and sometimes use both. Like I did for the 50 miler events. Fill them up with water, gatoraid, or whatever and don't use them. Sure it will add a few onzes more to your bike. But if you are doing a ride far from a trail head, your car, or other water source, it could save your life. When you finish the water on your kamel bag, you know you have at least 24 oz left on the water bottle to start riding back.
As a sing out in Croom says.... "Hydrate or Die"