Sounds like not too many E46 M3 owners on this thread? This was a pretty big annoyance on the e46, and the top solutions are simply clean body work (expensive), order euro bumper (expensive), paint (cheap), or clear reflectors(no thanks).
Bumper plugs will not work. Same as on the e46, they are not circular holes, rather stamped outlines of the reflectors.
Anyhow, painted reflectors are fine, it just comes down to getting this done by yourself or buying from somewhere Bimmian, that simply paints the OEM reflectors. I'll call tomorrow and report back what they have to say. I'm sure they will produce these soon enough, i just hope the lag is not too long.