So, here it is with the rack, etc.
Just got back from Hillsboro, about 550 miles. Stopped and looked things over pretty frequently, nothing got hot or fell off, so I guess we're OK!
Details, if anyone is curious:
F350 Dana front/10.5 rear, 4:88 gears and true track diff on both ends.
35 12.50 17s
Just short of 10' at the top of the rack.
8500 pounds with both of us in it and all the camping gear loaded.
11 mpg on the first fuel stop (lots of town, a big pass, and wall to wall holiday traffic) 13.25 mpg on the next stop (mostly easy 55/60 mph back roads and no real traffic).
I think things are coming together!