My colleagues and I study hydration for a living often in the longer duration work bouts similar to what happens across several days hunting. From our research some things to keep in mind
1. water quenches the thirst - NOT what you want - if your thirst is satisfied, you will drink less - possibly allowing greater dehydration
2. the electrolytes - esp salt in the sports drinks function 2 ways - a) at the kidney - they make your retain more fluid and b) b/c they are salty they MAKE YOU DRINK MORE - a good thing (same reason there are peanuts and pretzels on the bar - they sell more beer if they keep you thirsty)
3. Not drinking enough (as pointed out is a problem) MOST often the only problem with drinking too much is having to stop and urinate more often.
4. good info on the potential for bacteria in the rubber bladders - if you don't want to fool with cleaning often, use water in those.
5. WHEN FLUID SUPPLY IS LIMITED (such as you have only one canteen for the next couple hours or for the afternoon), SIPPING every 30 min is better than waiting and gulping the entire volume at once. When a large volume is taken at once, the bladder over reacts and dumps fluid. We hardly ever retain 100% of what we consume but we retain less when we gulp and more when we sip.
6. be safe and post pictures while I sweat out your elk season with jealously here in 100 degree (and same humidity) Alabama.
best of luck to all of you.
matt Green
ps - the research I spoke of is mostly published if any of you are nerd enough (like me) to want copies.
best: mg