You can double the capacity of any hitch w/ a weight distributing add on device for you hitch. If you are currently rated at 5k, then you will be good for 10k with this.
Keep this in mind though. Just because the hitch can handle 10,000 lbs doens't mean the vehicle can.
You should be able to buy a weight distribution device from any quality parts store, truck accessory store, or hitch retailer.