This stupidly placed light switch has been niggling around near the bottom of my list for nearly three years. It's probably sat there with its wires exposed for closer to thirteen, since the kitchen was remodeled by the previous owners.
I could have hunted down a plate and tried to saw a bit off I guess but we got a 3D printer for Christmas and I finally fixed it:
This was easier than I thought once I discovered that this sort of switch is a Decora Duplex. I grabbed this model from user KHF on 3D Warehouse (thanks!), chopped the edge off in FlashPrint, two failed prints (glue, then hairspray, then figuring out the temperature was wrong) and only slightly sliced open my thumb removing the supports. Welcome to the future!
OMG! I'm crying laughing...