Of course Wranglers have a good ground plane Mr Mac. If they didn't we'd all be using NGP (no ground plane) antennas which there is no need for. When the antenna and its mount are properly installed, the entire Jeep including its steel tub & frame combine to serve as a very good ground plane system for a CB or ham radio antenna.
Jaxon, your antenna doesn't have to extend above the soft top to work well. While the taller the antenna the better it works rule is true, even a 2' antenna mounted at tail light height like I run works very well when properly mounted and tuned for minimum SWR.
I've been involved with ham, cb, commercial, and military 2-way radios since the 60's so this isn't a subject I am unfamiliar with.