Like OM stated so eloquently, decrease all the weight of the other stuff. Lighter sleeping bag, tent, food..WATER. If you are always by water, then carry a little as possible. Then go after the camera gear. My first suggestion would be to get rid of a camera body.
As for packs, another suggestion would be to look at McHale packs. He makes lightweight ones that are designed to haul a lot of weight. Kifaru does as well. I am not an MR fan.