Cool beans.
How much weight are you working with?
Over 1000 lbs, and only 160 lbs of it is trailer tongue weight. The dogs, at 65 lbs each times five, weigh in at 325 lbs, the raised dog platform and storage structure in the van are made of 3/4" plywood and weigh god only knows what, we carry roughly 150 lbs of extraction and emergency gear (tool kit, hi-lift, heavy duty 3/8" chain, tire chains, wench etc.), 20 liters of water under the platform in the back of the van, then our packs, first aid (people and dogs), dog containment (x-pens, temporary fencing), full size spare, etc, never mind the under van protection (skid plates etc.). The primary driver for the trailer tongue weight is the three jerry cans on the tongue.
One might question the need for all this crap, but we have nothing on board that we haven't either used over the past six years traveling with our pack of dogs, or would have if we'd been smart enough to know we should have been carrying it. Although we haven't yet had a major extraction exercise of our own, we have had our share of flats in the middle of nowhere, been hung up on rocks (lost an oil pan 25 miles off road - hence the bullet proof skid plate), had to haul a downed monster ponderosa pine off some forest road, pull some dude in a jeep out of a ravine (imagine - an Astro Van rescuing a jeep. Oh well) etc.
We also have a 2" shackle lift to accommodate our 30" tires, which tends to flatten the springs as well because of the additional leverage the 4" of shackle provides.
Arrrg.
Helper springs from Michigan Truck Spring will go in sometime over Thanksgiving and should at least level the rig, perhaps even lift the rear a little beyond level. We'll just have to see.