Joe,

I have a cargo carrier/ ski box (Thule) for my VX and it fits just fine. It uses wide "u-bolts" to connect it to the rack and they are just wide enough to fit around our aero cross bars. The mounting points also slide back and forth in slots in the bottom of the box so I can position them where I need them, and there is still enough play left over to slide the box back and forth by a couple of inches once everything is in place.

To get bike racks on, though, I have had to get some universal adapters that a "normal" cross bar mounts to (above the VX's cross bars) and then mount the bike racks to that. Some others have found some standard roof rack mounts that fit into our mounting points and they've used standard cross bars with those, but it negates our aero cross bars.

See pictures below for various set ups.