Doc, I have an '08 Wrangler as well (2 Dr. A/T) and love it. Sad to say, but you're gas mileage dreaming...I get maybe 20-22 MPG on the road and 16-18 around town and I weigh a couple hundred pounds less than you do...sorry to bust that little bubble.
Even if you get 10MPG, you gonna LOVE this thing!
While under tow, the MPG in UNBELIEVABLE!
Your Wangler will NOT accumulate mileage while towing so no worries there. Crabby Mike's post pretty much covers all the towing requirements although I do not pull any fuses and I have to leave my installed negative battery post blade switch engaged to power my SMI Play N Stay Duo auxiliary braking system. I've never had a dead Jeep battery while towing...we drive maybe 300 to 350 miles at a stretch.
I also had a couple of 'dummy' keys made up...being an '08, you'll need to keep the ignition in the 'acc' position while in tow. The dummy allows you to leave the key in the ignition without fear of theft because, although the Jeep will start, it will only run for a second or two and then shut down with this key in the ignition.
IMHO, once you get set up and comfortable with towing the Jeep, you'll realize you have made a great decision with your toad.
Happy trails. Bob