[elhigh]

The Citroen 2CV (Deux Chevaux, "Two Horses") is a popular chassis start for a cheap and easy three wheeler - the rear suspension is already set up for it. Remove one rear suspension arm, and turn the other around to face the other direction. Where that wheel went out to the corner, it now is almost perfectly centered.

That's the "Lomax" kit car. A 2CV is already pretty darned lightweight, pulling off chassis bits and suspension bits lightens the load even further. But if you think Ecomodders try to get by with minimal power, you ain't seen nothin' yet: a last-gen 2CV doesn't wield much more power than a large Briggs and Stratton garden tractor engine.

I'm inclined to say that what you want is something that didn't have a pass-thru to the trunk. It's just a hunch, but you may find more steel for attaching your knocked-up rear single suspension.

Another thought: a compact pickup. Pull the bed, fab up whatever suspension you want and attach it to the radically shortened frame rails. You could adapt a heavy motorcycle shaft drive from the existing drivetrain to your new single rear wheel, or swap in a front drive system. You lose a fast 300-500lbs when you pull the bed, and the front stays heavy, so you should have decent traction in a front drive layout.