With the exception of PINK, some of ORANGE and spots in the quarry, I think a stock XJ can have a good time at the Badlands. There are bypasses for many of the major trouble spots. However, what may be considered "stock" tires wouldn't do. A decent all terrain tire would be needed at a minimum. In addition, a stock XJ would need SOLID recovery points front and rear should you need "recovery."
In addition, if you are worried at all about clear coat scratches and perhaps a few minor dings, then the Badlands isn't for you. It's not for the mall crawling crowd by any stretch. With care, knowledge of YOUR vehicle and YOUR driving skills, with an experienced spotter that wont let you do anything out of your realm, you can have a great time.