Seller says the car runs fine, what's the problem? Insure it first then drive any plates you can scrounge. Cops care more about insurance than if its legally registered en route.

Pick up some cheap diesel injector cleaner for adding to fuel, run it hard 75-85mph all the way home. Also empty the coolant at 2-bit carwash, add fresh water and 6hour coolant flush chemical product to clean out the radiator en route. First stop any auto parts store, settin the car up for high speed Italian tune-up.

Seriously hammer-down all the way back to West Va at top speed. The diesel engine will love you for it. Meanwhile if the wife's already whining and *****ing, take an airplane or bus and leave her home.