Did a quick look on cars.com and found about 300 JKU Sports ranging from ridiculous to sane (both in mods and price).
Here's a couple of the ridiculous ones BTW:
2013 Jeep Wrangler Unlimited Sport, $92,888 - Cars.com
2011 Jeep Wrangler Unlimited Rubicon, $79,900 - Cars.com
Okay, back on track, it looks like stockers are ranging from the mid twenties into the low thirties though I don't know what your local market will actually support.
If your local market will support those numbers, you can probably expect the dealer to offer $18K - $22K with a slight possibility of up to $24K.
Not sure how many dealers you have in your area but if there are more than a couple, look for one that offers a good deal on new but also has relatively few of what you are trading on their used lot and you might be able to get a little bit better trade.
Also, keep in mind that the dealer doesn't give a crap about any aftermarket mods when working a trade value with you but they will definitely use them to their advantage when selling it to the next guy.