License plate?? Duh??
If you give the case to the Feds, they will start with the rust obscured serial number from the axle.
Use their special lab resources to bring out the numbers from changes in the metal wave lengths and reactions to various dyes.
Research records back to the original plant that made the axle and to which assembly plant the part was shipped. Find out the color of the van, options installed and options that were not selected. Tire make and tread pattern will be especially noted.
Find the dealer that originally sold the van, what dealer options were installed and then interview every previous owner in succession as to why they had owned the van and for what purpose.
The trail ends three years later when the suspected last owners are not found and a BOLO is issued for a Party Of Interest.
All while the license plate is sitting in a box, in a closet somewhere in Virginia.