SeaRubi
Explorer
Looks like your question is already answered, so I will add an anecdote. Years ago, I met an Englishman who told me they would get a "field lift" on Range Rovers when they needed it by lowering the tailgate and bouncing up and down on it to pump up the self-leveling unit.
Also, our 93 Range Rover with air suspension was an order of magnitude better at self-leveling than our 89 Range Rover with coil springs and the Boge self-leveling unit.
same with my '94 LWB w/ air suspension. that thing never squatted.
Chris, have you thought about trying to adapt something from the guys at ORO with the AirRock system? It's expensive, but maybe a hybrid air suspension setup for the rear will come out around the same cost as trying to do some kind of fancy center-supported strut/spring thing, after parts, trail-and error and fabrication costs. just throwing ideas out there.