This could get pricy, but there are a couple of other ways to get the soft ride.
1 Go to a spring shop and explain your situation. You would want them to soften your main spring pack. Softer springs or remove leafs. Then they would need to beef up your overload springs. Probably the lower spring.
2 As in number 1, soften the main spring pack. Then add airbags to your existing overload springs.
3 Have a suspension seat installed in your truck.
Personally, I favor number 2. That is the way my '96 2500 Dodge was set up when I bought it. It had an aftermarket overload spring I replaced with airbags. It rode great empty. I decided I wanted less squat with my 4000 lb TC loaded. I had one leaf added to the spring pack. It reduced the squat by one inch, and definitely rode like a truck. I made that same mistake years ago, you would think I learned bett, but I did not.
Wayne