[diytech]

The 1990-92 (1st gen) Subaru Legacy LS had full air suspension (we have one). This was well before the "Outback" sensation, and the system is great at doing exactly what you describe. There are sensors in each air strut that determine ride height, and a complete pump, solenoid valve, and control system for the whole mess. A switch on the dash toggles nominal ride height from standard to off-road (about 2 3/4" difference, and limited to 35 mph to extend axle joint life).

The air ride is pure luxury, and the control system incorporates a really nice ride leveling system that runs all the time. The Achilles heel of the whole thing turned out to be the strut costs. The air pouches on the struts would deteriorate, and replacement struts were over $750 each. They also could not be refurbed the way they were made. People driving Subaru didn't want to shell out thousands at 70k miles, so most got converted with coil-overs.

If you found one in a junkyard, there could be solendoid valves, a nice compressor with dryer and tank, control box, and fittings and tubing for a pretty cheap price I would imagine (no demand).

I'm seriously considering doing a four corner airbag suspension. Mainly for leveling the van when we're parked - - including stealth camping.

It would also be nice to push it up to the top limit when going super slow over rough roads, or lower it down and soften it a little bit on a smooth freeway.
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In addition, I still would need to track down a controller, air tanks, and a compressor on this side. Not sure if I'll do it. However tonight we're camping outside of a ferry terminal and debating on whether to try to stealth with no blocks (heads down) or stick the blocks under the tires and sleep with our heads up. #firstworldproblems