Some sentimental background regarding a 22-year old Expedition?
The only UHaul car trailer I see tops out at 5290 pounds -- maybe a ton low -- so that doesn't seem to work. Putting the '02 on a car trailer you need to keep the combined (freight) truck, the trailer itself, and passengers and cargo weights in the tow vehicle down. All weight in the towing vehicle subtracts from it's 9000 pound towing capacity which is computed when it's empty.
a. Can your 2007 be flat towed (all 4 wheels on the pavement)? The linked towing guide notes the 2013 can pull 9,000 pounds and it's my guess the 2003 weighs no more than 7000 pounds completely empty.
b. Ya gonna be able to stop this rig if you can, lights, etc.? For a one-time event this could be complicated but appears within the capabilities of your 2013.
-- Chuck