Two things to add -
I have one of those Amphipod belts. I can't wear anything on my hips, it will bounce - anything that goes "around" has to go at my natural waist. The belt pulls my spine out of alignment, makes pelvic rotation difficult, it only carries 24 oz of water, and my 2-liter Intensity pack rides lighter when full than the Amphipod belt. I do still use it occasionally on runs of 7-8 miles, just barely long enough to need a few sips of water, but that's just mainly because the bottles are so much easier to clean and dry than a flexible bladder.
Also, overheating isn't necessarily related to hydration, but it very often is. 24 oz water wouldn't be nearly enough for me on a 10-mile run. I'm very prone to overheating, but in last summer's marathon training, there were only a couple of times on long runs in 95° heat that I even felt close to overheating, and that's because I'm really careful to keep up with hydration. A liter an hour does NOT replace everything I sweat out, but it's normally enough to keep me from overheating. I also have to be really careful to replace electrolytes, because I'm also prone to hyponatremia.
You might consider carrying enough plain water to pour over your head on occasion.
Speed comes from what you put behind you. - Judi Ketteler