You want to tow a car across the country with a 16 year old Jeep with a 4.0 Six, right?
On a dolly? Forget it. Have the car shipped. A compact car can weigh up to 3000 lbs and a proper trailer for car hauling is about 1500. There you're up to 4500. On the flat it will pull it but if the trailer brakes do not work perfectly, you will not be able to stop trust me on that. I pulled that much with no trailer brakes with my 98 ZJ a couple of times and its very dangerous. The ZJ brakes cannot stop more than about 1000 lbs in addition to its own weight. Then there's the cooling system and auto trans. Its just NOT a good idea, and I have towed with my 98 a lot, but upgraded many things(shocks, brakes tires, air bags in the rear coils added trailer brakes, etc) to make it safe at towing. My 07 WK Hemi tows the same load effortlessly.
2007 WK Limited Hemi QDII
1998 ZJ Laredo 4.0 Selectrac