wing nut that is at the top of the spare hold down bolt

I've spent a stupid amount of time on the interweb trying to find one of these. Looking to buy or find a source. This is NOT the big wide wingnut that holds the spare and jack base in place, but rather the wing nut that goes on top and holds the spare tire board and the metal cup down. I'm putting in a new trunk mat and don't want to have the wingnut and bolt end poke a hole in it. Hardware store wing nuts have the wings sticking way up. This wing nut looks like a factory air cleaner nut, but bigger.