I have an idea that when donating funds sufficient to get physical confirmation – plague, wall, etc, insist on a record “in honor of Anonymous” so that people internalize the idea that it is possible not to show off. You can add something like “anonymous lawyer”, or “in honor of Hungarian Jews” if you want.
Note also that we have yakum purkan for people who give wine for kiddush and not those who put names on the walls, as the latter already got their reward and do not need more encouragement. Nowadays, I hear same that upkeep funds are harder to find than new buildings.