I am 5 months late to your post but future surfboard and wrangler owners will appreciate it nonetheless
Amazon.com: Block Surf Single Wrap Surfboard Rack: Sports & Outdoors
These are perfect for transporting surfboards and skis when the Jeep is topless. One rack goes on top of your windshield, harnessed around the front roll bars. And the second wrack goes on your sound-bar, harnessed around the rear roll bars. I used it last summer (2012). I put on my 7'6" and my 5'8" and they fit snugly and I drove to my beach without worrying an ounce.
I will upload pictures with detailed instructions as soon as winter is over. It's the first day of spring here in NY but it still snowed like 3 inches today!
Cheers to all Surfer-Jeepers