Hey Rick,
I added a little collage to show some details...... and my wife still hasn't quit laughing that someone else thinks my rack is "cool" (I owe you for that favor). The thing could certainly use lots of modification, I built it at the last minute prior to a river trip last summer when I was going to be the main shuttle rig. There are three attachment points per side (three crossbars (redwood 2x6)with large sturdy gutter-mount feet). There are two 10 foot 2x6's that run the length of the roof of the old Suburban, and they are cut along the bottom to match the contour of the roof, and a long strip of closed cell foam epoxied to the cut to compensate for inaccuracies. This way, the weight is actually distributed along the roof, and the gutter attachments are there to resist Upward forces. The vertical cradles are made from T-111 siding from my garage, when I put a couple windows in. They are made of two pieces, separated by a piece of 2x6. they sit down over the crossbar 2x6's, and a couple deck screws driven in on each side. the racks can go on the front and back cross-bars for a 9' spacing, or rear & center for 6' spacing, or front & center for 3.5' spacing (bikes).
The thing looks like heck, but the vertical cradles hold the yaks so well, that you can drive around at lower speeds without any boat movement. I do intend to make a set of tubular vertical cradles out of 3/4 copper tubing and pipe insulation, mainly for increased aerodynamics (hard to actually say that word in relation to a suburban). Anyway, hope you find something useful in here, I'll be happy to get back to ya on any other questions.
Thanks, and Cheers,
Bob