wow, that's a pretty sweet setup. that's almost exactly what I'm looking for - although an additional perpendicular bar that runs the length of the van on both sides would be better suited to my needs.
my van must have lost its plastic covers, cause I'm just seeing two pairs of very rusty bolt heads. I'll take a some pictures and measurements once the snow clears - if you can confirm that the attachment points have the same spread on my 12 and your 16, then I'm golden.
thanks very much both of yous