Thank you!

Part of the point of this exercise is for the object to "look right" to overload::Method, if anyone cares to look. I don't want it to look like @{} is available if it's one of the unimplemented methods on that particular instance.

Your point about leaking packages all over is well-taken. I suspect that "looks right" functionality is less important than that. Perhaps I'll implement both solutions and let the user specify which behavior they want (with details of the trade-offs in the documentation).