That's why you need more progressive spring rate if you run empty. Using some type of overload that only engages once spring deflection passes a desired point is how you can preserve that empty ride. Using the lower StableLoads that can be engaged/disengaged based on usage is another method.
For me, using air bags to level out and disengaging my overload springs gave me a soft but wallowing ride. Once I was able to engage the springs and use the bags, I found a happy medium and comfortable ride even if rear axle weight could vary by a 1000 lbs based on what I carried.