I used to carry multiple Camelbaks as well when going on all-day(7-8 hour) mountain bike rides in the subtropical heat and humidity of the Big Island of Hawaii. You can carry a basic Camelbak (or more than one) sideways like a fanny pack fairly comfortably. I used to carry the initial 100oz in the big HAWG backpack and then rotate in the two other 70oz bladders from the fanny pack position when the 100oz bladder ran dry. Plus I carried two water bottles of sports drink so you don't totally screw up your electrolytes making up for the sweating. I never felt the approx 280 oz and we were usually riding pretty far and fast.