The 10% is based on the actual trailer weight, not the maximum trailer weight. In your case I wouldn't go over 150 lbs. Not only does the hitch need to support the tongue, but the hitch needs to stay attached to the car. Since GM has a 1,000 lb trailer weight limit, this tells me the Cruze is designed to safely handle up to a 150 lb tongue.
When using a cargo rack you also have to take into account the additional stress of rack rotation (outside edges of the rack going up and down). A trailer doesn't have this type of stress because it has wheels on each side to keep the trailer frame level as well as a hitch ball to allow movement in multiple directions, including side to side rotation.
The fact that your hitch has a tongue weight rating of 200 lbs gives you a maximum weight you can put on the hitch. The question you need answered is what is the maximum your Cruze can handle. You then take the lower value. The Cruze can probably handle 200 lbs, but given the safety margins built into the manual's weight limits and the side to side stresses that exist with a cargo rack that don't exist with a trailer, I wouldn't go more than 150 lbs.