Need advice on using Cargo Carrier w/ Hidden Hitch

I am looking at purchasing a cargo carrier that fits a 2" trailer hitch. Does anyone have any experience with these? I have read that the tongue weight for the Jetta Wagon is 200 lbs, and this carrier has a 400 lb capacity, thus I would need to be carefully of not overloading it.
The carriers I am looking at are from etrailer (see link)
http://www.etrailer.com/c-cc2.htm

Thanks for the assist.