Originally Posted by Brian Carlton

The vehicle is going to sit level with no load in the trunk and about 1/2 tank of fuel. If you then add 800 lb. of load, no springs in the world are going to keep a level attitude. Either you start out high in the rear and end up level.......or you start out level and end up with a sagging look when you apply the load.

I'd increase the thickness of the spring pads until the unloaded height is just barely acceptable (high).

There is probably nothing wrong with your springs.