I know this may not be the answer you're looking for, but you may really benefit from buying this rack through a local, smaller sporting goods or bike shop.

I used to work in a bike shop, and we could always call our distributor of rack systems and give them the specs on the car and what the person wanted to carry, and they would tell us exactly what pieces were required. There are a lot of little bits (which is probably why you found it frustrating to try to figure out on the manufacturer websites--I agree with you there!) that you have to have for a successful installation.

We ordered lots of racks when I worked there, and they always installed exactly as intended, with no extra parts or parts missing that had to be ordered after the fact. A lot of times, smaller bike stores will install the rack for free or for a really nominal fee.

You'll know when you go in or call and ask the question if the person can really help you, or if they're out to overcharge you or sell you a lot of things you don't need. I would get at least two quotes for the full system just to make double-sure.

The prices we got from our distributor, plus the store's markup, were always either right at or even less than buying directly from the manufacturer's online store. If you find a good, reputable bike shop (or sporting goods shop) then you should get the same or better deal than figuring it all out on your own.

Good luck! I hope there's someone local to you who can help you out.