Got the van up on the rack today for some fine tunin' (special thanks to Jeremy and his shop Matrix Integrated for letting me take up every inch of space on their alignment rack).
Guess what? The suspension geometry was exactly where I expected it to be! Only had to change the toe a tad and straighten the steering wheel. The axle came from Quadvan's original alignment with 2 deg (in the wrong direction) caster bushings. Measured out today at 3.5 deg caster. So with a factory installed 0 degree bushing, I'd have 5.5 deg (exactly what I designed for). I want to drive for a while with 3.5 deg caster and see how it works. Then at some point I'll put in a zero deg bushing and compare. It already drives much better than when it was a Quadvan (with 1.5 deg of caster).
Getting very close to having this radius arm axle installation kit dialed in and ready for sale.