The mini-pack will make a difference, but if you want to cure the bad ride altogether, then get the shocks too. The PACE system will make the truck more balanced, and not feel like the front is a pogo, and the rear is a buckboard. The truck will go over bumps or whatever terrain without bucking/hopping around.
Here's an example as best I can describe in words. How many washboard roads have you been down? Know the sensation, You hit them too fast, and the truck feels like the rear is jumping around, throw that same washboard into an intersection when making a turn, and the rear of the truck jumps around, and you instantly let up or hit the brakes, because you feel like your losing control. Or you hit a bump or hole, and you think your teeth are going to fall out.
Well with the KORE system, none of that happens. Washboard is soaked up, you can accelerate over it, and the rear stays planted, never jumping or hopping around.
Make a turn in a crappy intersection, and you can accelerate through it, and the truck stays planted. Hit a hole or bump, and it is asborbed. Fact is, you can go over the same terrain you normally go slow for, much faster.
Seriously consider fixing the problem. Rearching the springs won't do much, except take away money you could have spent on a real fix.