I'd focus more on the roof racks first, as the product selection for our vehicle without the roof rails appears to be quite limited. I only know of two brands that offer products designed specifically for our vehicle that don't have the rails installed from the factory: Inno racks and Rhino Racks. Other brands might offer a rack that they consider a "universal fit", but there's no guarantee that they'll work.
As far as a cargo carrier, I can't provide much advice. There are so many on the market, so you might just have to pick the one that fits your needs, wants, and budget yourself. I think the biggest things to keep in mind are: 1. the overall length of the carrier, since these cars are kind of short to begin with; and 2. if the back of the cargo carrier will clear the rear liftgate when it's open. If I were in your shoes and looking for something new, I'd probably stop by a local retailer (like a camping or sporting goods store) who sells them and see if they could do a couple of test fits with different carriers.
Here are two threads about the cargo carriers a few here have been using:
disappointed-factory-crossbars-t549751.html
thule-cargo-carriers-any-luck-t509871.html
Please come back and let us know what you end up going with.