Others have made great comments. Keeping it simple, if your rear bumper is 10' behind the center of the axels, and your pin is 30' ahead (a 3:1 ratio) (to keep the math easy) for every 100 lbs you put on the bumper, you reduce pin weight by 33 lbs (100/3).
It gets complicated when you start moving things from ahead to behind as you have to figure what proportion comes off the pin vs the axels, and then how much additional comes off the pin based on where it got put behind the axels.
In the end, you have to move a lot of weight to get a significant reduction in pin weight. And likely a lot of that will have to moved again when you get to camp. Most of the heavy stuff can't be moved very easily - water tank, batteries, etc.
Better to just leave stuff, especially heavy stuff, at home. Or dump the slider, and get a much lighter standard hitch with a Reese Revolution...