I need a new bladder for mine. I'm getting the widemouth bladder, easier to shovel ice in the sucker.
I fill the thing up to the top with ice, then fill in with cold water. Feels great on my back on a hot day, yes the original Camelbak Classic 70 ozzer has a chest strap too, so it's comfy.
It's really not an issue over a long day, it gets progressively lighter as you empty it. Most mini-marts have free ice and water out of the soda fountains. Most any place with a soda fountain will
have a sink next to it for cleaning maintenance, I'd chock it full of ice and top off with water, nobody's said a word to me, usually because I'm buying gas/trailmix/smokes anyway.
One key thing i failed to mention is on a hot day, after you take your sip, blow back the water that remains in the hose into the bladder.
Prevents your next sip from being piss-warm and funky tasting.
Camelback saves storage space and lets me drink between gas stops.
That's why I carry it on my back as designed. I need my tankbag space when on a trip. Lots of stuff I normally carry in a topcase go in the tankbag on a longer run.