I've been using the Evoc Hip pack race 3L this season with great success.
Fits 2.5L of water (1.5Lbladder +1L bottle) and Sony Alpha 7 with 2 Prime lenses easily along with tools and basic snacks.
Sometimes i ditch the bladder and fit even more crap in it like gform kneepads and gloves and glasses.
Does not move around at all and thr back is far more ventilated than the Camelback.
Pinner, winner, chicken dinne