You're right the CG location is influenced more by the weight furthest away from the CG. However if you want your kayak to be trim without any cargo it is necessary to locate the paddler (and the cockpit) to achieve the correct balance or ballast will have to be added. When you are dealing with only two items the kayak and the paddler, the paddler has to be located correctly to achieve the trim. Then when cargo is carried it will be split between front and back compartments as necessary to achieve the correct trim for that gross weight as well as the expected sea conditions.

: That was clear as mud, so here goes another stab at it. A 200 lb. weight
: located 1 inch from the center of mass has the same effect on trim (bow-up
: or bow-down) as a 20 lb. weight 10 inches away, or 2 lbs. 100 inches away.
: Ergo large loading variations in the cockpit have little effect on trim,
: although they will affect how high the boat rides in the water.