Update: I ended up getting a pretty good deal on some rack ears locally, so I went for it. They fit if you use a few washers as spacers—just put the cover on, turn it on its side and stack washers until they’re flush with the edge of the cover. I may actually end up attaching the washers to the rack ears at some point since it’s a pretty good solution.
So currently I’m not urgently needing rack ears, and with my solution it means they don’t have to be redesigned. I may order a pair from you though for my monomachine at some point!