Here's an interesting accessory combo license plate holder and crank handle lock hasp for use with your own padlock. I believe this item was designed before electric start was offered.
I have a cast iron one of these. They are nice.
Well I gave this one my best effort, but no patent found.
I have a feeling that no patent was applied for or issued.
Notice it holds the crank upright. I could use one of those.. for the license plate, too.
I also have a cast-iron one on my 15. They work great and look good too.