1953 South Dakota 1st First Issue HAM RADIO W9HPE License Plate - Sort Of

Description

This is my best guess, that these are the call letters off of a 1953 First Year of Issue HAM Radio license plate from South Dakota.    Here's my logic.  Glen Martin, from Hopewell, S.D. owned these call letters in 1931.  He didn't always renew his license, because in 1953 there's no record that I could find of him owning these call letters, but no one else did either in 1953, and I'm guessing he used an old license to allow him to put these call letters on his 1953 South Dakota license plate.  In 1956, it appears that Arthur Nicola, from Indianapolis, IN acquired the call letters, and had them until 2009 or so.  I think that Glen sheared off the numbers from his license plate after it was used in 1953 on his vehicle.  The size and lettering is just too coincidental for me to think otherwise.  But, I'm not a HAM Radio expert, and so I'd like to hear what the rest of you might think.  The colors (white on dark red) match with 1953 South Dakota, as does the location of the call letters in 1953.
If you collect First Issue HAM plates or South Dakota plates, this could me a pretty rare filler plate until a complete original comes along.
I was going to find a 1953 South Dakota license plate, and cut out the letters as a similar shape, and spot weld this onto it to make the plate "more complete", but I've got too many other projects.
Email any questions, and feel free to give me your opinions as to what else this might be.