Tough lookin rig! Looks like that is a Lexus? If so, to confirm, you are running stock Toyota LC rear springs and front torsion bars? IF that's correct, are your springs the AHC version or non-AHC?
This sounds like what I may need to do. My 06 LX is my wife's daily driver. Only added weight so far is a roof rack, but when we go for an expedition, we pack several hundred pounds of gear in back and on the roof. We probably do 2-3 trips per year. For such intermittent heavy loads, the...