The following was recounted to me by someone named "Frodis" about the Milk Muds Wacky Pack ringer shirt:
I am 28 years old and I still have most of the 1979-80's Wacky Package reissue cards. ... Anyhow, my reason for writing is that I still have a "Blunder Bread" Wacky Packages t-shirt. I got it for my birthday when I was 6 (1981). It's quite small, with a red ring collar. So, you can definitely remove that from your "rumored to exist" section. I also specifically remember seeing a Crust t-shirt, as well as a "Milk Muds" t-shirt at JC Penney department store in Matteson, IL sometime in 1981.